Session 2: Hip and Knee
18. November
09:00 - 10:30
Lokale: 102-103
Chairmen: Kirill Gromov & Andreas Kappel
Cecilie Henkel, Unnur Styrkársdóttir, Ole B. Pedersen, Kári Stefánsson, Anders Troelsen
Clinical Orthopaedic Research Hvidovre (CORH), Department of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre; deCODE genetics; Department of Clinical Immunology, Zealand University Hospital, Køge; deCODE genetics; Clinical Academic Group: Research OsteoArthritis Denmark (CAG ROAD), Department of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre
Background: The broad disease spectrum of osteoarthritis (OA) ranges from mild symptoms to debilitating joint destruction, ultimately demanding joint replacement. Though numerous studies have determined a substantial genetic contribution to OA development, it is uncertain whether genetic factors determine disease progression—and thereby the need for surgical intervention.
Aim: Our aim was to explore whether genetic associations for hip OA differ between patients treated surgically and non-surgically, respectively.
Materials and Methods: We performed 2 large-scale genome-wide association studies (GWAS) in each of 3 cohorts from Denmark, Iceland, and the United Kingdom. In each cohort, we identified primary hip OA cases (without known injuries or other joint diseases) and assigned them to either a surgical (hOA-S) or non-surgical (hOA-NS) case group. The case groups were individually compared with a healthy control group without any OA diagnoses, and these GWAS results were then combined in 2 treatment-specific fixed-effects inverse variance meta- analyses. Genotyping in the Danish and Icelandic cohorts was done using Illumina Infinium Global Screening Array, and Affymetrix Axiom arrays were used in the British cohort. Variants with high-quality imputation (>0.8) in all 3 cohorts were included in the meta-analyses. Using a weighted Holm-Bonferroni method, we determined statistical significance at a variant class-specific familywise error rate of 0.05.
Results: 38,068 cases were included in the 2 meta-analyses, representing 20,221 surgical and 17,847 non-surgical hip OA patients. We identified 34 significant associations, of which 7 were novel (on chromosomes 3, 5, 16, 17 and 21). All 7 markers were significant in hOA-S (p= 7.01×10- 8) and nonsignificant in hOA-NS (1 marker with p=0.04, 6 with p=0.11). Additionally, 2 of the replicated significant markers in hOA-S had p>0.05 in hOA-NS.
Interpretation / Conclusion: Our findings include 7 novel risk loci for hip OA that all show differences in genetic associations between surgically and non-surgically treated hip OA patients. On this basis, we suggest that the genetic associations of hip OA vary with the need for joint replacement.
Clinical Orthopaedic Research Hvidovre (CORH), Department of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre; deCODE genetics; Department of Clinical Immunology, Zealand University Hospital, Køge; deCODE genetics; Clinical Academic Group: Research OsteoArthritis Denmark (CAG ROAD), Department of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre
Background: The broad disease spectrum of osteoarthritis (OA) ranges from mild symptoms to debilitating joint destruction, ultimately demanding joint replacement. Though numerous studies have determined a substantial genetic contribution to OA development, it is uncertain whether genetic factors determine disease progression—and thereby the need for surgical intervention.
Aim: Our aim was to explore whether genetic associations for hip OA differ between patients treated surgically and non-surgically, respectively.
Materials and Methods: We performed 2 large-scale genome-wide association studies (GWAS) in each of 3 cohorts from Denmark, Iceland, and the United Kingdom. In each cohort, we identified primary hip OA cases (without known injuries or other joint diseases) and assigned them to either a surgical (hOA-S) or non-surgical (hOA-NS) case group. The case groups were individually compared with a healthy control group without any OA diagnoses, and these GWAS results were then combined in 2 treatment-specific fixed-effects inverse variance meta- analyses. Genotyping in the Danish and Icelandic cohorts was done using Illumina Infinium Global Screening Array, and Affymetrix Axiom arrays were used in the British cohort. Variants with high-quality imputation (>0.8) in all 3 cohorts were included in the meta-analyses. Using a weighted Holm-Bonferroni method, we determined statistical significance at a variant class-specific familywise error rate of 0.05.
Results: 38,068 cases were included in the 2 meta-analyses, representing 20,221 surgical and 17,847 non-surgical hip OA patients. We identified 34 significant associations, of which 7 were novel (on chromosomes 3, 5, 16, 17 and 21). All 7 markers were significant in hOA-S (p= 7.01×10- 8) and nonsignificant in hOA-NS (1 marker with p=0.04, 6 with p=0.11). Additionally, 2 of the replicated significant markers in hOA-S had p>0.05 in hOA-NS.
Interpretation / Conclusion: Our findings include 7 novel risk loci for hip OA that all show differences in genetic associations between surgically and non-surgically treated hip OA patients. On this basis, we suggest that the genetic associations of hip OA vary with the need for joint replacement.
Lars Lykke Hermansen, Bjarke Viberg, Søren Overgaard
Department of Orthopaedics, Hospital of South West Jutland, Esbjerg, and The Orthopaedic Research Unit, Department of Orthopaedic Surgery and Traumatology, Odense University Hospital, Odense; Department of Orthopaedic Surgery and Traumatology, Odense University Hospital, Odense and Department of Orthopedic Surgery and Traumatology, Lillebaelt Hospital, University hospital of Southern Denmark; Department of Orthopedic Surgery and Traumatology, Bispebjerg Hospital og Institute of Clinical Medicine, Copenhagen University
Background: Dislocation of total hip arthroplasties (THA) leads to poorer quality of life for the patients, but since dislocations are often treated with closed reduction, they are traditionally not registered in orthopedic arthroplasty registers worldwide.
Aim: This study aimed to create an algorithm designed to identify cases of dislocations of THAs with high sensitivity (SN), specificity (SP), and positive predictive value (PPV) based on codes from the Danish National Patient Register (DNPR).
Materials and Methods: All patients (n=31,762) with primary osteoarthritis undergoing THA from 01.01.2010 to 31.12.2014 were included from the Danish Hip Arthroplasty Register (DHR). We extracted available data for every hospital contact in the DNPR during a two-year follow-up period, both admissions to orthopaedic and non-orthopaedic departments and outpatient emergency room contacts. We conducted a nationwide review of 5,096 patient files to register all dislocations and applied codes. We designed the algorithm using a stepwise approach by adding codes in each step to continuously increase SN, while at the same time keeping the SP and PPV high.
Results: We identified 1,890 hip dislocations among 1,094 of the included 31,762 THAs. More than 70 different diagnoses and 55 procedural codes were coupled to the hospital contacts with dislocation. A combination of the correct codes (DT840+KNFH20) yielded a SN of 62.7% and a PPV of 97.9%. Adding alternative and often applied codes in three steps (DS730, KNFH(20;21;22;00;02)) increased the SN to 91.3%, while the PPV was kept at 93.3%. An additional step (DT840 alone, acute admissions) increased SN to 95.4% but at the expense of an unacceptable decrease in the PPV to 81.8%. A minor effort in reviewing 0.3- 1% of patient files could raise the PPV to 96.6% in the last two steps. SP was, in all steps, greater than 99%.
Interpretation / Conclusion: The developed algorithm demonstrated a SN of 91.3% and a PPV at 93.3% for identifying dislocations, which we consider acceptable. Higher SN is possible but at the expense of drastically lowering the PPV and are not feasible for register studies. In perspective, this kind of algorithm may be used in Danish quality registers.
Department of Orthopaedics, Hospital of South West Jutland, Esbjerg, and The Orthopaedic Research Unit, Department of Orthopaedic Surgery and Traumatology, Odense University Hospital, Odense; Department of Orthopaedic Surgery and Traumatology, Odense University Hospital, Odense and Department of Orthopedic Surgery and Traumatology, Lillebaelt Hospital, University hospital of Southern Denmark; Department of Orthopedic Surgery and Traumatology, Bispebjerg Hospital og Institute of Clinical Medicine, Copenhagen University
Background: Dislocation of total hip arthroplasties (THA) leads to poorer quality of life for the patients, but since dislocations are often treated with closed reduction, they are traditionally not registered in orthopedic arthroplasty registers worldwide.
Aim: This study aimed to create an algorithm designed to identify cases of dislocations of THAs with high sensitivity (SN), specificity (SP), and positive predictive value (PPV) based on codes from the Danish National Patient Register (DNPR).
Materials and Methods: All patients (n=31,762) with primary osteoarthritis undergoing THA from 01.01.2010 to 31.12.2014 were included from the Danish Hip Arthroplasty Register (DHR). We extracted available data for every hospital contact in the DNPR during a two-year follow-up period, both admissions to orthopaedic and non-orthopaedic departments and outpatient emergency room contacts. We conducted a nationwide review of 5,096 patient files to register all dislocations and applied codes. We designed the algorithm using a stepwise approach by adding codes in each step to continuously increase SN, while at the same time keeping the SP and PPV high.
Results: We identified 1,890 hip dislocations among 1,094 of the included 31,762 THAs. More than 70 different diagnoses and 55 procedural codes were coupled to the hospital contacts with dislocation. A combination of the correct codes (DT840+KNFH20) yielded a SN of 62.7% and a PPV of 97.9%. Adding alternative and often applied codes in three steps (DS730, KNFH(20;21;22;00;02)) increased the SN to 91.3%, while the PPV was kept at 93.3%. An additional step (DT840 alone, acute admissions) increased SN to 95.4% but at the expense of an unacceptable decrease in the PPV to 81.8%. A minor effort in reviewing 0.3- 1% of patient files could raise the PPV to 96.6% in the last two steps. SP was, in all steps, greater than 99%.
Interpretation / Conclusion: The developed algorithm demonstrated a SN of 91.3% and a PPV at 93.3% for identifying dislocations, which we consider acceptable. Higher SN is possible but at the expense of drastically lowering the PPV and are not feasible for register studies. In perspective, this kind of algorithm may be used in Danish quality registers.
Tobias Dahl Vind, Peter Bo Jørgensen, Dovydas Vainorius, Stig Storgaard Jakobsen, Kjeld Søballe, Maiken Stilling
Dept of Orthopaedics, Aarhus University Hospital; Department of Clinical Medicine, Aarhus University Hospital; University Clinic for Hand, Hip and Knee Surgery, Hospital Unit West; Dept of Orthopaedics, Aarhus University Hospital; Department of Orthopedics, Aarhus University Hospital; Hand Section, Dept of Orthopaedics, Aarhus University Hospital
Background: The Exeter short stem is 25 mm shorter than the standard length v40 Exeter stem (Stryker) and intended for use in a narrow femoral diaphysis.
Aim: The purpose of the study was to evaluate the migration pattern of the cemented Exeter short stem.
Materials and Methods: In a prospective single-center cohort study, 23 patients (21 female) mean age 78 (range 70-89) with hip osteoarthritis and Dorr Type A femurs were included. Preoperative DXA was used to group patients into normal (> -1) and low (<-1) T-score. Components were the collarless polished double-tapered Exeter short stem type N°1 L125. Patients were followed for two years with model-based RSA (stem migration), regular hip radiographs (stem position and cementation quality), Oxford Hip Score (OHS) and VAS pain.
Results: At two-years follow-up, the stems subsided 1.48 mm (CI95 1.69; 1.26) and retroverted 0.45° (CI95 0.01; 0.88). From 12 to 24 months, stem subsidence was 0.18 mm (CI95 0.1; 0.25) (p=0.001) and retroversion was -0.04° (CI95 -0.27; 0.18) (p=0.70). T-score and stem subsidence correlated (rho=0.48; p=0.025) and patients with normal T- score (n=7) had 0.42 mm (CI95 -0.01; 0.85) less subsidence as compared to patients with low T-score (n=15) (p=0.054). Stems in varus position (n=10) subsided 1.7 mm (CI95% 1.35; 2.05) compared to 1.33 mm (CI95% 1.05; 1.60) for stems in neutral position (n=13) (p=0.07). Postoperative cementation quality did not influence stem migration. OHS improved to 40.7 (CI95 36.8; 44.7) and VAS pain at rest and activity decreased to 5mm and 10mm, respectively (p<0.001).
Interpretation / Conclusion: The migration pattern of the cemented ESS was similar to reports for the cemented standard length Exeter stem. Low preoperative T-score and varus stem- position showed a tendency for higher stem migration and should be studied as risk factors for failure in larger studies of cemented polished stems.
Dept of Orthopaedics, Aarhus University Hospital; Department of Clinical Medicine, Aarhus University Hospital; University Clinic for Hand, Hip and Knee Surgery, Hospital Unit West; Dept of Orthopaedics, Aarhus University Hospital; Department of Orthopedics, Aarhus University Hospital; Hand Section, Dept of Orthopaedics, Aarhus University Hospital
Background: The Exeter short stem is 25 mm shorter than the standard length v40 Exeter stem (Stryker) and intended for use in a narrow femoral diaphysis.
Aim: The purpose of the study was to evaluate the migration pattern of the cemented Exeter short stem.
Materials and Methods: In a prospective single-center cohort study, 23 patients (21 female) mean age 78 (range 70-89) with hip osteoarthritis and Dorr Type A femurs were included. Preoperative DXA was used to group patients into normal (> -1) and low (<-1) T-score. Components were the collarless polished double-tapered Exeter short stem type N°1 L125. Patients were followed for two years with model-based RSA (stem migration), regular hip radiographs (stem position and cementation quality), Oxford Hip Score (OHS) and VAS pain.
Results: At two-years follow-up, the stems subsided 1.48 mm (CI95 1.69; 1.26) and retroverted 0.45° (CI95 0.01; 0.88). From 12 to 24 months, stem subsidence was 0.18 mm (CI95 0.1; 0.25) (p=0.001) and retroversion was -0.04° (CI95 -0.27; 0.18) (p=0.70). T-score and stem subsidence correlated (rho=0.48; p=0.025) and patients with normal T- score (n=7) had 0.42 mm (CI95 -0.01; 0.85) less subsidence as compared to patients with low T-score (n=15) (p=0.054). Stems in varus position (n=10) subsided 1.7 mm (CI95% 1.35; 2.05) compared to 1.33 mm (CI95% 1.05; 1.60) for stems in neutral position (n=13) (p=0.07). Postoperative cementation quality did not influence stem migration. OHS improved to 40.7 (CI95 36.8; 44.7) and VAS pain at rest and activity decreased to 5mm and 10mm, respectively (p<0.001).
Interpretation / Conclusion: The migration pattern of the cemented ESS was similar to reports for the cemented standard length Exeter stem. Low preoperative T-score and varus stem- position showed a tendency for higher stem migration and should be studied as risk factors for failure in larger studies of cemented polished stems.
Christoffer Bruun Korfitsen, Inger Mechlenburg, Jane Schwartz Leonhardt , Lone Ramer Mikkelsen, Søren Overgaard
Christoffer Bruun Korfitsen, The Parker Institute, Bispebjerg and Frederiksberg Hospital, the Capital Region, Frederiksberg and The Danish Health Authority; Inger Mechlenburg, Department of Orthopedic Surgery, Aarhus University Hospital and Department of Clinical Medicine, Aarhus University, Denmark and Department of Public Health, Aarhus University; Jane Schwartz Leonhardt, Department of Orthopaedic Surgery, Vejle Hospital; Lone Ramer Mikkelsen, Department of Clinical Medicine, Aarhus University and Elective Surgery Centre, Silkeborg Regional Hospital; Søren Overgaard, Department of Orthopaedic Surgery, Bispebjerg Hospital, Copenhagen University Hospital, and Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen and The Orthopedic Research Unit, Department of Orthopedic Surgery and Traumatology, Odense University Hospital, Odense, and Department of Clinical Research, University of Southern Denmark
Background: Hip precautions are routinely prescribed to decrease dislocation rates after total hip arthroplasty (THA) using a posterior approach.
Aim: The purpose of this systematic review was to determine whether hip precautions influence early recovery after THA.
Materials and Methods: Randomised and non-randomised controlled trials comparing postoperative precautions after THA with minimal or no precautions were included. MEDLINE, EMBASE, PEDRO and Cinahl were searched in March 2016 and updated in June 2020. Screening of eligible studies, data extraction and risk of bias assessment were conducted by two reviewers. Critical outcome were hip dislocations three months post-THA. Important outcomes included late hip dislocation, patient-reported function, functional performance, reoperation, pain, health-related quality of life, and return to work. Inverse variance random effects and Mantel- Haenszel fixed-effects meta-analyses were performed to synthesise the results. A guideline panel used the Grading of Recommendations Assessment and Evaluation (GRADE) approach to rate the certainty of evidence. The Protocol was registered at the Danish Health Authority website.
Results: Two randomised and four non-randomised trials, including 3,778 participants, were included. There was low certainty of evidence for no difference in risk of dislocation within three months after THA following hip precautions compared to no or minimal precautions (risk ratio: 1.38, 95% CI: 0.73-2.59), low certainty of evidence for a small effect on patient-reported function favouring no or minimal precautions (risk ratio: 1.54, 95% CI: 1.18-2.02), and very low certainty of evidence for a small effect on functional performance favouring no or minimal precautions (risk ratio: 0.64, 95% CI: 0.48-0.85). Moderate, low, and very low certainty of evidence was found for no difference on any other important outcomes.
Interpretation / Conclusion: Precautions will possibly not reduce the risk of dislocation. Both patient-reported function and functional performance were slightly better with no or minimal precautions. Recommendation: Do not routinely instruct patients in hip precautions after posterior approach THA because there is possibly no effect on the risk of hip dislocations.
Christoffer Bruun Korfitsen, The Parker Institute, Bispebjerg and Frederiksberg Hospital, the Capital Region, Frederiksberg and The Danish Health Authority; Inger Mechlenburg, Department of Orthopedic Surgery, Aarhus University Hospital and Department of Clinical Medicine, Aarhus University, Denmark and Department of Public Health, Aarhus University; Jane Schwartz Leonhardt, Department of Orthopaedic Surgery, Vejle Hospital; Lone Ramer Mikkelsen, Department of Clinical Medicine, Aarhus University and Elective Surgery Centre, Silkeborg Regional Hospital; Søren Overgaard, Department of Orthopaedic Surgery, Bispebjerg Hospital, Copenhagen University Hospital, and Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen and The Orthopedic Research Unit, Department of Orthopedic Surgery and Traumatology, Odense University Hospital, Odense, and Department of Clinical Research, University of Southern Denmark
Background: Hip precautions are routinely prescribed to decrease dislocation rates after total hip arthroplasty (THA) using a posterior approach.
Aim: The purpose of this systematic review was to determine whether hip precautions influence early recovery after THA.
Materials and Methods: Randomised and non-randomised controlled trials comparing postoperative precautions after THA with minimal or no precautions were included. MEDLINE, EMBASE, PEDRO and Cinahl were searched in March 2016 and updated in June 2020. Screening of eligible studies, data extraction and risk of bias assessment were conducted by two reviewers. Critical outcome were hip dislocations three months post-THA. Important outcomes included late hip dislocation, patient-reported function, functional performance, reoperation, pain, health-related quality of life, and return to work. Inverse variance random effects and Mantel- Haenszel fixed-effects meta-analyses were performed to synthesise the results. A guideline panel used the Grading of Recommendations Assessment and Evaluation (GRADE) approach to rate the certainty of evidence. The Protocol was registered at the Danish Health Authority website.
Results: Two randomised and four non-randomised trials, including 3,778 participants, were included. There was low certainty of evidence for no difference in risk of dislocation within three months after THA following hip precautions compared to no or minimal precautions (risk ratio: 1.38, 95% CI: 0.73-2.59), low certainty of evidence for a small effect on patient-reported function favouring no or minimal precautions (risk ratio: 1.54, 95% CI: 1.18-2.02), and very low certainty of evidence for a small effect on functional performance favouring no or minimal precautions (risk ratio: 0.64, 95% CI: 0.48-0.85). Moderate, low, and very low certainty of evidence was found for no difference on any other important outcomes.
Interpretation / Conclusion: Precautions will possibly not reduce the risk of dislocation. Both patient-reported function and functional performance were slightly better with no or minimal precautions. Recommendation: Do not routinely instruct patients in hip precautions after posterior approach THA because there is possibly no effect on the risk of hip dislocations.
Christian Emil Husted, Henrik Husted, Christian Skovgaard Nielsen, Mette Mikkelsen, Anders Troelsen, Kirill Gromov
Department of Orthopedic Surgery, Copenhagen University Hospital, Hvidovre, Denmark
Background: Discharge on the day of surgery (DDOS) after total hip arthroplasty (THA) and total knee arthroplasty (TKA) has been shown to be safe in selected patients. Concerns have been that discharging patients on the day of surgery (DOS) could lead to an increased burden on other parts of the health care system when compared to patients not discharged on the DOS (nDDOS).
Aim: To investigate whether discharging patients on the day of surgery (DOS) after THA and TKA leads to increased contacts with the primary care sector or other departments within the secondary care sector.
Materials and Methods: Prospective data on 261 consecutive patients scheduled for outpatient THA (n=135) and TKA (n=126) were collected as part of a previous cohort study. 33% of THA patients and 37% of TKA patients were discharged on the DOS. Readmissions within 3 months after surgery were recorded. Contacts with the discharging department, other departments, and primary care physicians within 3 weeks were registered.
Results: No statistically significant differences were found when comparing DDOS patients and patients not discharged on the DOS (nDDOS) with regards to readmissions, physical contacts with the discharging department, and contacts with other departments as well as general practitioners. THA DDOS patients had significantly fewer contacts with the discharging department by telephone than THA nDDOS patients. TKA DDOS patients had significantly more contacts with the discharging department by telephone than TKA nDDOS patients.
Interpretation / Conclusion: Patients discharged on the DOS following THA or TKA generally have similar postoperative contacts with the health care system when compared to patients not discharged on the DOS.
Department of Orthopedic Surgery, Copenhagen University Hospital, Hvidovre, Denmark
Background: Discharge on the day of surgery (DDOS) after total hip arthroplasty (THA) and total knee arthroplasty (TKA) has been shown to be safe in selected patients. Concerns have been that discharging patients on the day of surgery (DOS) could lead to an increased burden on other parts of the health care system when compared to patients not discharged on the DOS (nDDOS).
Aim: To investigate whether discharging patients on the day of surgery (DOS) after THA and TKA leads to increased contacts with the primary care sector or other departments within the secondary care sector.
Materials and Methods: Prospective data on 261 consecutive patients scheduled for outpatient THA (n=135) and TKA (n=126) were collected as part of a previous cohort study. 33% of THA patients and 37% of TKA patients were discharged on the DOS. Readmissions within 3 months after surgery were recorded. Contacts with the discharging department, other departments, and primary care physicians within 3 weeks were registered.
Results: No statistically significant differences were found when comparing DDOS patients and patients not discharged on the DOS (nDDOS) with regards to readmissions, physical contacts with the discharging department, and contacts with other departments as well as general practitioners. THA DDOS patients had significantly fewer contacts with the discharging department by telephone than THA nDDOS patients. TKA DDOS patients had significantly more contacts with the discharging department by telephone than TKA nDDOS patients.
Interpretation / Conclusion: Patients discharged on the DOS following THA or TKA generally have similar postoperative contacts with the health care system when compared to patients not discharged on the DOS.
Cecilie Henkel, Unnur Styrkársdóttir, Ole B. Pedersen, Kári Stefánsson, Anders Troelsen
Clinical Orthopaedic Research Hvidovre (CORH), Department of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre; deCODE genetics; Department of Clinical Immunology, Zealand University Hospital, Køge; deCODE genetics; Clinical Academic Group: Research OsteoArthritis Denmark (CAG ROAD), Department of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre
Background: Osteoarthritis (OA) is a multifactorial disease with a genetic contribution of up to 50% and around 100 known genetic risk loci. Despite the apparent differences in personal and socio-economic consequences between different grades of OA, it is unknown whether disease severity, and thereby the need for surgical treatment, is determined by genetic factors.
Aim: We aimed to investigate whether genetic associations for knee OA differ between patients who received surgical treatment (kOA-S) and patients who did not (kOA-NS).
Materials and Methods: We defined cases as patients with primary knee OA and no known injuries or other joint diseases. As controls, we included healthy persons without any OA diagnoses. In each of 3 large cohorts from Denmark, Iceland and the United Kingdom, we performed 2 treatment-specific genome-wide association studies (knee OA vs healthy controls), which we subsequently joined in 2 fixed-effects inverse variance meta-analyses for kOA-S and kOA-NS, respectively. The Danish and Icelandic cohorts were genotyped using Illumina Infinium Global Screening Array, and Affymetrix Axiom arrays were used in the British cohort. Imputation was performed, and variants with imputation quality >0.8 in all 3 cohorts were included in the meta-analyses. Statistical significance was set at a familywise error rate of 0.05 (variant class-specific) determined by a weighted Holm-Bonferroni method.
Results: The 2 meta-analyses included 61,151 knee OA cases, of which 22,525 were surgical and 38,626 were non-surgical. We identified 17 significant markers, including 3 novel ones (located on chromosomes 2 and 3). The 3 novel markers were all statistically significant in kOA-S (p=3.06×10-9) and undoubtedly non-significant in kOA-NS (p=0.27) —a pattern also seen in 2 of the replicated markers. 1 marker was only significant in the nonsurgical group (kOA-NS p=1.19×10-13 vs kOA-S p=0.0047).
Interpretation / Conclusion: We have identified 3 novel markers for knee OA, all of which indicate a difference in genetic associations between surgically and non-surgically treated knee OA—a difference which we also found in 3 replicated markers. In conclusion, our findings suggest that the genetic associations of knee OA vary with the course of treatment.
Clinical Orthopaedic Research Hvidovre (CORH), Department of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre; deCODE genetics; Department of Clinical Immunology, Zealand University Hospital, Køge; deCODE genetics; Clinical Academic Group: Research OsteoArthritis Denmark (CAG ROAD), Department of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre
Background: Osteoarthritis (OA) is a multifactorial disease with a genetic contribution of up to 50% and around 100 known genetic risk loci. Despite the apparent differences in personal and socio-economic consequences between different grades of OA, it is unknown whether disease severity, and thereby the need for surgical treatment, is determined by genetic factors.
Aim: We aimed to investigate whether genetic associations for knee OA differ between patients who received surgical treatment (kOA-S) and patients who did not (kOA-NS).
Materials and Methods: We defined cases as patients with primary knee OA and no known injuries or other joint diseases. As controls, we included healthy persons without any OA diagnoses. In each of 3 large cohorts from Denmark, Iceland and the United Kingdom, we performed 2 treatment-specific genome-wide association studies (knee OA vs healthy controls), which we subsequently joined in 2 fixed-effects inverse variance meta-analyses for kOA-S and kOA-NS, respectively. The Danish and Icelandic cohorts were genotyped using Illumina Infinium Global Screening Array, and Affymetrix Axiom arrays were used in the British cohort. Imputation was performed, and variants with imputation quality >0.8 in all 3 cohorts were included in the meta-analyses. Statistical significance was set at a familywise error rate of 0.05 (variant class-specific) determined by a weighted Holm-Bonferroni method.
Results: The 2 meta-analyses included 61,151 knee OA cases, of which 22,525 were surgical and 38,626 were non-surgical. We identified 17 significant markers, including 3 novel ones (located on chromosomes 2 and 3). The 3 novel markers were all statistically significant in kOA-S (p=3.06×10-9) and undoubtedly non-significant in kOA-NS (p=0.27) —a pattern also seen in 2 of the replicated markers. 1 marker was only significant in the nonsurgical group (kOA-NS p=1.19×10-13 vs kOA-S p=0.0047).
Interpretation / Conclusion: We have identified 3 novel markers for knee OA, all of which indicate a difference in genetic associations between surgically and non-surgically treated knee OA—a difference which we also found in 3 replicated markers. In conclusion, our findings suggest that the genetic associations of knee OA vary with the course of treatment.
Lauge Bundvad, Mette Mikkelsen, Lina H. Ingelsrud, Christian S. Nielsen, Kirill Gromov , Anders Troelsen
Department of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre, Copenhagen, Denmark
Background: The Personalized Knee System (Zimmer, Warsaw, IN, USA) is a new Total Knee Arthroplasty (TKA) design. This non-designer study's primary motivation was internal quality assessment as part of implementing the Persona TKA at our institution.
Aim: We aimed to examine implant safety and patient self-reported pain and function by determining two- year survival rate and patient-reported outcome measures (PROMs). The secondary objective was to examine the proportions of patients achieving postoperative PROM scores that reflected a patient acceptable symptom state (PASS) and a change exceeding the minimal important change (MIC).
Materials and Methods: We included 568 patients (643 knees) operated with the Persona TKA at one institution between December 2015 and May 2019. We calculated the implant survival rate using the Kaplan-Meier analysis. Patients answered the PROMs; the Oxford Knee Score (OKS) and the Forgotten Joint Score (FJS) preoperatively, and at three months, one year, and two years postoperatively. Changes in PROM scores were analyzed with paired t-tests. We used previously published cut- off values to examine the proportions of patients achieving 2-year postoperative PROM scores that reflected a PASS (OKS 30 points) and a change exceeding the MIC (OKS 8 points and FJS 14 points).
Results: 18 patients had 19 primary revisions resulting in a Kaplan-Meier estimated 2-year survival rate of 0.96. The group achieved a median increase in the OKS from 22.33 preoperatively to 38.16 two years after surgery (p < 0.001). 75% surpassed the PASS value, and 72% achieved the MIC. The group achieved a mean increase in the FJS from 16.09 preoperatively to 57.54 two years after surgery (p < 0.001), and 76% achieved the MIC.
Interpretation / Conclusion: The two-year survival rate for the Persona TKA were comparable to other established TKA designs, and both PROMs increased significantly. Furthermore, approximately three-fourths of the patients in our study had postoperative PROM scores that reflected well-being and a change score considered important by the average patient.
Department of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre, Copenhagen, Denmark
Background: The Personalized Knee System (Zimmer, Warsaw, IN, USA) is a new Total Knee Arthroplasty (TKA) design. This non-designer study's primary motivation was internal quality assessment as part of implementing the Persona TKA at our institution.
Aim: We aimed to examine implant safety and patient self-reported pain and function by determining two- year survival rate and patient-reported outcome measures (PROMs). The secondary objective was to examine the proportions of patients achieving postoperative PROM scores that reflected a patient acceptable symptom state (PASS) and a change exceeding the minimal important change (MIC).
Materials and Methods: We included 568 patients (643 knees) operated with the Persona TKA at one institution between December 2015 and May 2019. We calculated the implant survival rate using the Kaplan-Meier analysis. Patients answered the PROMs; the Oxford Knee Score (OKS) and the Forgotten Joint Score (FJS) preoperatively, and at three months, one year, and two years postoperatively. Changes in PROM scores were analyzed with paired t-tests. We used previously published cut- off values to examine the proportions of patients achieving 2-year postoperative PROM scores that reflected a PASS (OKS 30 points) and a change exceeding the MIC (OKS 8 points and FJS 14 points).
Results: 18 patients had 19 primary revisions resulting in a Kaplan-Meier estimated 2-year survival rate of 0.96. The group achieved a median increase in the OKS from 22.33 preoperatively to 38.16 two years after surgery (p < 0.001). 75% surpassed the PASS value, and 72% achieved the MIC. The group achieved a mean increase in the FJS from 16.09 preoperatively to 57.54 two years after surgery (p < 0.001), and 76% achieved the MIC.
Interpretation / Conclusion: The two-year survival rate for the Persona TKA were comparable to other established TKA designs, and both PROMs increased significantly. Furthermore, approximately three-fourths of the patients in our study had postoperative PROM scores that reflected well-being and a change score considered important by the average patient.
Henriette Appel Holm, Per Wagner Kristensen, Lasse Enkebølle Rasmussen
Background: Up to 20 % of all patients having a TKR are less satisfied. Predicting long term outcome would be of key importance in meeting patients’ expectations. expectations.
Aim: The aim is to investigate whether preop Oxford Knee Score (OKS), can predict long term results for TKR patients.
Materials and Methods: OKS was collected in a prospective cohort study (preop, 1-5 and 10 years) in 200 consecutive patients with primary osteoarthritis, operated during 2006-9 with the Vanguard TKR. The change in OKS was determined for each patient. The patients were divided in thirds depending on their preop OKS: Lower (OKS < 21, Middle (22 < OKS < 27), High (OKS > 27). Differences between groups were measured by Anova, followed by Tukeys Multiple Comparison post hoc analysis. Similarly, 1 year results were divided in 3 groups, Lower (patients with OKS < 40), Middle (41 < OKS < 44), high (OKS > 45), to determine if 1 year results predicts long term results. Odds-ratio was measured using Babtista Pike and Chi-square test.
Results: 91 females (average age 64.68, range 36-82, BMI = 29.88, range 21-47) and 109 males (average age 66.58, range 46-85, BMI = 29.18 range 19-43 were included. At 10 years, 46/200 (23%) was lost to follow-up (38 dead, 8 for other reasons), 12 were revised. Mean OKS increased from 23.15 points to a maximum of 44.84 points at 5 years with a small decline to 43.58 points at 10 years. Median change over 10 years was dependent of preop OKS, since preop OKS < 21 changed 25.92 points; 22 < preop OKS < 27 changed 19.94 points, and preop OKS > 27 changed 14.78 points (p< 0.001 between the 3 groups). At 10 years, comparing patients with high and low preop OKS showed an odds ratio = 3.054 (p=0.009) for an OKS above 45 for patients with a high preop OKS. Patients with an OKS > 45 at 1 year had significantly higher OKS at 10 year than the patients with an OKS < 45 at 1 year (p=0.0036)
Interpretation / Conclusion: The increase in OKS depends on the preop score, with the highest gain for patients with the lowest preop score. Patients with a low preop OKS have significantly lower chance of getting an excellent long term result. Overall, preop OKS somehow predicts long term results and if known, may aid in bridging patient expectations with outcome. outcome.
Background: Up to 20 % of all patients having a TKR are less satisfied. Predicting long term outcome would be of key importance in meeting patients’ expectations. expectations.
Aim: The aim is to investigate whether preop Oxford Knee Score (OKS), can predict long term results for TKR patients.
Materials and Methods: OKS was collected in a prospective cohort study (preop, 1-5 and 10 years) in 200 consecutive patients with primary osteoarthritis, operated during 2006-9 with the Vanguard TKR. The change in OKS was determined for each patient. The patients were divided in thirds depending on their preop OKS: Lower (OKS < 21, Middle (22 < OKS < 27), High (OKS > 27). Differences between groups were measured by Anova, followed by Tukeys Multiple Comparison post hoc analysis. Similarly, 1 year results were divided in 3 groups, Lower (patients with OKS < 40), Middle (41 < OKS < 44), high (OKS > 45), to determine if 1 year results predicts long term results. Odds-ratio was measured using Babtista Pike and Chi-square test.
Results: 91 females (average age 64.68, range 36-82, BMI = 29.88, range 21-47) and 109 males (average age 66.58, range 46-85, BMI = 29.18 range 19-43 were included. At 10 years, 46/200 (23%) was lost to follow-up (38 dead, 8 for other reasons), 12 were revised. Mean OKS increased from 23.15 points to a maximum of 44.84 points at 5 years with a small decline to 43.58 points at 10 years. Median change over 10 years was dependent of preop OKS, since preop OKS < 21 changed 25.92 points; 22 < preop OKS < 27 changed 19.94 points, and preop OKS > 27 changed 14.78 points (p< 0.001 between the 3 groups). At 10 years, comparing patients with high and low preop OKS showed an odds ratio = 3.054 (p=0.009) for an OKS above 45 for patients with a high preop OKS. Patients with an OKS > 45 at 1 year had significantly higher OKS at 10 year than the patients with an OKS < 45 at 1 year (p=0.0036)
Interpretation / Conclusion: The increase in OKS depends on the preop score, with the highest gain for patients with the lowest preop score. Patients with a low preop OKS have significantly lower chance of getting an excellent long term result. Overall, preop OKS somehow predicts long term results and if known, may aid in bridging patient expectations with outcome. outcome.
Martin Lindberg-Larsen, Pelle Baggesgaard Petersen, Yasemin Corap, Kirill Gromov, Christoffer Calov Jørgensen, Henrik Kehlet
Orthopaedic Research Unit, Department of Orthopaedic Surgery and Traumatology, Odense University Hospital, Department of Clinical Research, University of Southern Denmark; Lundbeck Foundation Centre for Fast-track Hip and Knee Arthroplasty, Copenhagen, Denmark; Section for Surgical Pathophysiology, Rigshospitalet, Copenhagen, Denmark; Department of Orthopedics, Hvidovre Hospital, Hvidovre, Denmark
Background: Limited data exist on fast-track protocols in relation to revision knee arthroplasty.
Aim: The aim of this study was to report length of stay (LOS), risk of LOS > 5 days and readmission = 90 days after revision knee arthroplasty in centers with a well-established fast-track protocol in both primary and revision surgery.
Materials and Methods: An observational cohort study from the Centre for Fast-track Hip and Knee Replacement and the Danish Knee Arthroplasty Register. We included elective aseptic major component revision knee arthroplasties consecutively from 6 dedicated fast- track centers from 2010 to 2018.
Results: 1439 revision knee arthroplasties were analyzed, including 900 total revisions, 171 large partial revisions (revision of either femoral or tibia component) and 368 revisions of unicompartmental knee arthroplasty (UKA) to total knee arthroplasty (TKA). Mean age was 65 years (SD 10.9) and 66% were females. Mean LOS was 3.7 days (SD 3.9) in the study period, but decreased to 2.4 days (SD 1.3) in 2018. Risk factors for LOS > 5 days was = 1 previous revision, use of walking aid, BMI>35, ages < 50, 70-79 and =80 years, whereas revision of UKA to TKA and large partial revision were negatively associated. The 90-day readmission and mortality risk was 9.1% and 0.5%. Cardiac disease and use of walking aid were associated with increased risk of readmission =90 days.
Interpretation / Conclusion: Elective aseptic major component revision knee arthroplasty using similar fast-track protocols as in primary TKA is safe with short and decreasing LOS.
Orthopaedic Research Unit, Department of Orthopaedic Surgery and Traumatology, Odense University Hospital, Department of Clinical Research, University of Southern Denmark; Lundbeck Foundation Centre for Fast-track Hip and Knee Arthroplasty, Copenhagen, Denmark; Section for Surgical Pathophysiology, Rigshospitalet, Copenhagen, Denmark; Department of Orthopedics, Hvidovre Hospital, Hvidovre, Denmark
Background: Limited data exist on fast-track protocols in relation to revision knee arthroplasty.
Aim: The aim of this study was to report length of stay (LOS), risk of LOS > 5 days and readmission = 90 days after revision knee arthroplasty in centers with a well-established fast-track protocol in both primary and revision surgery.
Materials and Methods: An observational cohort study from the Centre for Fast-track Hip and Knee Replacement and the Danish Knee Arthroplasty Register. We included elective aseptic major component revision knee arthroplasties consecutively from 6 dedicated fast- track centers from 2010 to 2018.
Results: 1439 revision knee arthroplasties were analyzed, including 900 total revisions, 171 large partial revisions (revision of either femoral or tibia component) and 368 revisions of unicompartmental knee arthroplasty (UKA) to total knee arthroplasty (TKA). Mean age was 65 years (SD 10.9) and 66% were females. Mean LOS was 3.7 days (SD 3.9) in the study period, but decreased to 2.4 days (SD 1.3) in 2018. Risk factors for LOS > 5 days was = 1 previous revision, use of walking aid, BMI>35, ages < 50, 70-79 and =80 years, whereas revision of UKA to TKA and large partial revision were negatively associated. The 90-day readmission and mortality risk was 9.1% and 0.5%. Cardiac disease and use of walking aid were associated with increased risk of readmission =90 days.
Interpretation / Conclusion: Elective aseptic major component revision knee arthroplasty using similar fast-track protocols as in primary TKA is safe with short and decreasing LOS.
Christian Bredgaard Jensen, Anders Troelsen, Christoffer Calov Jørgensen, Henrik Kehlet, Kirill Gromov
Clinical Orthopaedic Research Hvidovre (CORH), Department of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre; Section for Surgical Pathophysiology, Rigshospitalet; Centre for Fast-track Hip and Knee Arthroplasty, Denmark.
Background: The indications for unicompartmental knee arthroplasty (UKA) have become more liberal. As such UKA surgery is performed in age and Body Mass Index (BMI) extremes. While the influence of these patient characteristics on length of stay (LOS) and readmission in total knee arthroplasty surgery is well documented, the same evidence in UKA is lacking.
Aim: This study aims to investigate the effect of BMI and age on day of surgery (DOS) discharge, prolonged admission and 90-day readmission after UKA surgery.
Materials and Methods: This study included 3897 UKA patients with complete data on BMI between 2010-2018 from 8 fast-track arthroplasty centres. Patients were divided into 5 BMI (kg/m2) groups according to the World Health Organization. Patients were also divided into 5 age groups. Differences between BMI and age groups in DOS-discharge (LOS=0 days), prolonged admission (LOS>2 days), 90-day readmission was investigated using chi squared analysis and mixed effect models adjusted for patient characteristics and comorbidity using surgical centre as a random effect.
Results: Within the cohort median BMI was 28.1 (IQR=25.4-31.5), mean age was 66.2 years (SD=9.4), and median LOS was 1 day (IQR=0- 1). Most patients were overweight (43%) and aged between 61-70 years (37%). DOS- discharge was achieved in 25.5% of patients with no significant differences between BMI groups. DOS-discharge was less likely in UKA patients aged >70 years (Age 71-80; odds ratio (OR) = 0.71 [0.58 – 0.88], p= 0.002. Age > 80; OR = 0.18 [0.10 – 0.34], p<0.001) compared to patients aged 61-70 years. Prolonged admission occurred in 7.5% of patients but was not affected by BMI or age in the adjusted analysis. 90-day readmission was more likely in very obese patients (OR = 1.86 [1.12 – 3.10], p= 0.017) and patients aged 71-80 (OR = 1.54 [1.12 – 2.13], p=0.008) compared to patients with normal BMI and age 61-70 years, respectively.
Interpretation / Conclusion: Age above 70 years decreased the likelihood of DOS-discharge after UKA surgery, while BMI did not affect DOS-discharge. BMI and age did not affect prolonged admission. High BMI and advanced age increased the likelihood of 90-day readmission. This should be considered as a part of the shared decision-making process.
Clinical Orthopaedic Research Hvidovre (CORH), Department of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre; Section for Surgical Pathophysiology, Rigshospitalet; Centre for Fast-track Hip and Knee Arthroplasty, Denmark.
Background: The indications for unicompartmental knee arthroplasty (UKA) have become more liberal. As such UKA surgery is performed in age and Body Mass Index (BMI) extremes. While the influence of these patient characteristics on length of stay (LOS) and readmission in total knee arthroplasty surgery is well documented, the same evidence in UKA is lacking.
Aim: This study aims to investigate the effect of BMI and age on day of surgery (DOS) discharge, prolonged admission and 90-day readmission after UKA surgery.
Materials and Methods: This study included 3897 UKA patients with complete data on BMI between 2010-2018 from 8 fast-track arthroplasty centres. Patients were divided into 5 BMI (kg/m2) groups according to the World Health Organization. Patients were also divided into 5 age groups. Differences between BMI and age groups in DOS-discharge (LOS=0 days), prolonged admission (LOS>2 days), 90-day readmission was investigated using chi squared analysis and mixed effect models adjusted for patient characteristics and comorbidity using surgical centre as a random effect.
Results: Within the cohort median BMI was 28.1 (IQR=25.4-31.5), mean age was 66.2 years (SD=9.4), and median LOS was 1 day (IQR=0- 1). Most patients were overweight (43%) and aged between 61-70 years (37%). DOS- discharge was achieved in 25.5% of patients with no significant differences between BMI groups. DOS-discharge was less likely in UKA patients aged >70 years (Age 71-80; odds ratio (OR) = 0.71 [0.58 – 0.88], p= 0.002. Age > 80; OR = 0.18 [0.10 – 0.34], p<0.001) compared to patients aged 61-70 years. Prolonged admission occurred in 7.5% of patients but was not affected by BMI or age in the adjusted analysis. 90-day readmission was more likely in very obese patients (OR = 1.86 [1.12 – 3.10], p= 0.017) and patients aged 71-80 (OR = 1.54 [1.12 – 2.13], p=0.008) compared to patients with normal BMI and age 61-70 years, respectively.
Interpretation / Conclusion: Age above 70 years decreased the likelihood of DOS-discharge after UKA surgery, while BMI did not affect DOS-discharge. BMI and age did not affect prolonged admission. High BMI and advanced age increased the likelihood of 90-day readmission. This should be considered as a part of the shared decision-making process.