Peroneal Nerve Palsy After Total Knee Arthroplasty.

Background: Common peroneal nerve palsy (CPNP) is a rare complication of total knee arthroplasty (TKA). It may lead to impaired function and pain. The purpose of this study was to determine the frequency and outcome of CPNP in a single orthopedic unit and to identify potential risk factors. Methods: This is a single-center study using the hospital's prospectively collected quality registry. All TKAs from 2002 to 2022 were included and followed up from 3 to 24 months with a follow-up rate of 98.4%. The local joint register was reviewed to identify patients with CPNP and used to extract data regarding the operation and the patients with and without CPNP. The groups were compared to identify possible risk factors for nerve injury. The medical records of the patients with CPNP were reviewed to determine the CPNPs' severity and outcome, and their preoperative radiographs were analyzed and compared to a control group with no nerve injury. Results: A total of 7704 TKAs were included, and 25 CPNPs were identified (0.32%). Complete palsies occurred in 18 cases, and partial palsies in 7. Postoperative epidural anesthesia, preoperative excessive valgus, and female sex were significant risk factors. Body mass index and age were not associated with CPNP. Two-thirds of the complete palsies had complete recovery, and four-fifths of the partial palsies recovered. Conclusions: The incidence of CPNP was 0.32%, and risk factors were epidural anesthesia, excessive valgus, and female sex. Most patients with CPNP recovered completely. Partial palsies had better outcomes than complete palsies in our cohort.

No Increased Risk of Venous Thromboembolism in High-Risk Patients Continuing Their Dose of 75 mg Aspirin Compared to Healthier Patients Given Low-Molecular-Weight Heparin.

BACKGROUND: Optimum venous thromboembolism (VTE) prophylaxis for patients undergoing total hip or knee arthroplasty remains undefined. The purpose of this study is to compare complication rates among total joint arthroplasty patients using either low-dose aspirin (75 mg once daily) or low-molecular-weight heparin (LMWH; Fragmin/dalteparin 5000 U) for VTE prophylaxis. METHODS: This is a prospective observational study. All total hip or knee arthroplasties from 2014 to 2020 were included. One thousand eighty-four patients already taking aspirin 75 mg as primary or secondary prophylaxis for cardiovascular disease continued their daily aspirin dose throughout their hospital stay and after discharge without any other kind of thromboprophylaxis. Five thousand ten patients not already taking aspirin were given LMWH for 12-14 days starting the day of surgery. Both groups consisted of patients undergoing either primary or revision total hip or knee arthroplasty. The aspirin group was older (73 ± 7.8 vs 66 ± 10.2 years, P < .01, 95% CI -7.6, -6.3) with more comorbidities but otherwise did not differ from the LMWH group. Outcome measures were recorded at 3-month follow-up and included the following complications: clinically deep venous thrombosis (DVT), pulmonary embolism (PE), deep infection, blood transfusion, and death. RESULTS: The aspirin group had 0.28% DVT and 0.28% PE, and the LMWH group had 0.24% DVT and 0.16% PE (P = .42 and .74, respectively). No difference in deep infection, allogenic blood transfusion, or mortality was found. CONCLUSION: No statistically significant difference in complication rates was found between aspirin 75 mg and LMWH used for VTE prophylaxis. Aspirin 75 mg daily is safe for VTE prophylaxis after total hip or knee arthroplasty.

Low wear rate at 6-year follow-up of vitamin E-infused cross-linked polyethylene: a randomised trial using 32- and 36-mm heads.

BACKGROUND: Free radicals formed in the cross-linking process may over time alter the mechanical properties of highly cross-linked polyethylene. Vitamin E-infused highly cross-linked polyethylene was therefore developed to achieve low wear-rate and good mechanical properties in the long term. AIM: To present 6-year results from the initial randomised controlled trial. PATIENTS AND METHODS: We measured wear and periacetabular bone remodelling in cementless total hip arthroplasty; 32- or 36-mm Biolox Delta heads and vitamin E-infused highly cross-linked polyethylene (E-Poly) were used. Markerless radiosterometric analysis measured the in vivo wear and dual energy x-ray absorptiometry was used to analyse bone remodelling in 40 hips at 6-year follow-up. RESULTS: In the proximal direction the wear for 32- and 36-mm heads was 0.15 mm (95% confidence interval [CI], 0.08-0.21) and 0.06 mm (95% CI, -0.002-0.12), respectively (p = 0. 015). However, between 3 months and 6 years (excluding the period of "bedding in"), the proximal wear for 32- and 36-mm heads was 0.10 mm (95% CI, 0.05-0.15) and 0.05 mm (95% CI, -0.01-0.11), respectively (p = 0.12). The annual proximal wear rate for 32- and 36-mm heads from 3 months to 6 years was 0.02 mm and 0.01 mm, respectively. There was no difference in bone remodelling around the cup from baseline to 6 years for the total material and no differences between study groups. CONCLUSION: Wear of this vitamin E-infused highly cross-linked polyethylene is still low at 6-year follow-up, with no significant difference in wear from 3 months to 6 years between 32- and 36-mm heads.

A Trend for Increased Risk of Revision Surgery due to Deep Infection following Fast-Track Hip Arthroplasty.

Rates of revision surgery due to deep infection following total hip arthroplasty (THA) increased at a Norwegian hospital following implementation of fast-track procedures. The purpose of this study was to determine whether selected demographic (age and sex) and clinical (body mass index, American Society of Anesthesiologists (ASA) classification, surgery duration, length of hospital stay, cemented versus uncemented prosthesis, and fast-track procedures) factors were associated with higher risk of revision surgery due to deep infection following THA. In a prospective designed study 4,406 patients undergoing primary THA between January 2001 and January 2013 where included. Rates of infection-related revision surgery within 3 months of THA were higher among males and among patients who received fast-track THA. Adjusting for sex and age, the implemented fast-track elements were significantly associated with increased risk of revision surgery. Risk of infection-related revision surgery was unrelated to body mass index, physical status, surgery duration, length of hospital stay, and prosthesis type. Because local infiltration analgesia, drain cessation, and early mobilization were introduced in combination, it could not be determined which component or combination of components imposed the increased risk. The findings in this small sample raise concern about fast-track THA but require replication in other samples.

E-vitamin infused highly cross-linked polyethylene: RSA results from a randomised controlled trial using 32 mm and 36 mm ceramic heads.

BACKGROUND: Polyethylene wear has been a major cause of revision of cementless total hip replacements. Highly cross-linked polyethylene has been developed to increase mechanical resistance to wear. However, cross-linking from irradiation of the polyethylene generates free radicals and these can oxidise in vivo and might over time alter the initial mechanical properties. Vitamin-E infused highly cross-linked polyethylene has been developed to reduce the amount of free radicals without compromising the mechanical properties. PURPOSE: To measure wear of vitamin E infused highly cross-linked polyethylene and compare wear between 2 different head sizes. METHODS: In a prospective randomised study between 32 mm and 36 mm Biolox® delta heads in 50 hips we analysed the in vivo wear of the E-poly™ with markerless radiostereometry. RESULTS: Mean (95% CI) wear for the total material was 0.041 mm (0.015-0.066) in the vertical direction and 0.177 mm (0.155-0.200) in the total 3D direction. After the anticipated period of bedding-in we found no statistically significant differences in wear from three months to 2 years in vertical and total 3D directions. Although statistical significant differences between 32 mm and 36 mm heads were found in the total 3D direction we cannot conclude that there are significant clinical important differences in wear comparing these head sizes. CONCLUSIONS: This study shows promising early results with very low wear, even for 36 mm heads, but long term follow-up is necessary to evaluate if this polyethylene will provide low wear and good mechanical properties in the long-term.

Worse patient-reported outcome after lateral approach than after anterior and posterolateral approach in primary hip arthroplasty. A cross-sectional questionnaire study of 1,476 patients 1-3 years after surgery.

BACKGROUND: The surgical approach in total hip arthroplasty (THA) is often based on surgeon preference and local traditions. The anterior muscle-sparing approach has recently gained popularity in Europe. We tested the hypothesis that patient satisfaction, pain, function, and health-related quality of life (HRQoL) after THA is not related to the surgical approach. PATIENTS: 1,476 patients identified through the Norwegian Arthroplasty Register were sent questionnaires 1-3 years after undergoing THA in the period from January 2008 to June 2010. Patient-reported outcome measures (PROMs) included the hip disability osteoarthritis outcome score (HOOS), the Western Ontario and McMaster Universities osteoarthritis index (WOMAC), health-related quality of life (EQ-5D-3L), visual analog scales (VAS) addressing pain and satisfaction, and questions about complications. 1,273 patients completed the questionnaires and were included in the analysis. RESULTS: Adjusted HOOS scores for pain, other symptoms, activities of daily living (ADL), sport/recreation, and quality of life were significantly worse (p < 0.001 to p = 0.03) for the lateral approach than for the anterior approach and the posterolateral approach (mean differences: 3.2-5.0). These results were related to more patient-reported limping with the lateral approach than with the anterior and posterolateral approaches (25% vs. 12% and 13%, respectively; p < 0.001). INTERPRETATION: Patients operated with the lateral approach reported worse outcomes 1-3 years after THA surgery. Self-reported limping occurred twice as often in patients who underwent THA with a lateral approach than in those who underwent THA with an anterior or posterolateral approach. There were no significant differences in patient-reported outcomes after THA between those who underwent THA with a posterolateral approach and those who underwent THA with an anterior approach.

Reverse hybrid and cemented hip replacement compared using radiostereometry and dual-energy X-ray absorptiometry: 43 hips followed for 2 years in a prospective trial.

BACKGROUND AND PURPOSE: Total hip replacement (THR) with a reverse hybrid (RH), a combination of a cemented polyethylene cup and a cementless femoral stem, has been increasingly used in Scandinavia. In a randomized trial, we compared an RH THR with a proximal hydroxyapatite- (HA-) coated stem to a conventional cemented THR. Both groups received the same polyethylene cup. PATIENTS AND METHODS: 51 patients (52 hips) were included. Radiostereometry (RSA) and dual-energy X-ray absorptiometry (DEXA) were performed postoperatively and after 6, 12, and 24 months. 42 patients (43 hips) were followed for 2 years. RESULTS: Mean cup rotation around the x-axis was 0.13° for the cemented group and -0.24° for the RH group (p = 0.03). Cup migration in the other axes, and stem migration and wear were similar between the 2 study groups. Bone remodeling around the cup was also similar between the groups. Bone loss in Gruen zone 1 was 18% for the cementless stems, as compared to an increase of 1.4% for the cemented ones (p < 0.001). Bone loss was similar in the other Gruen zones. Harris hip score and Oxford hip score were similar pre- and postoperatively in the 2 groups. INTERPRETATION: In the present study, RH THR with a cementless hydroxyapatite-coated stem and conventional cemented THR did not show any major differences regarding stem migration and bone loss after 2 years of follow-up.

Is reverse hybrid hip replacement the solution?

BACKGROUND AND PURPOSE: Reverse hybrid hip replacement uses a cemented all-polyethylene cup and an uncemented stem. Despite increasing use of this method in Scandinavia, there has been very little documentation of results. We have therefore analyzed the results from the Norwegian Arthroplasty Register (NAR), with up to 10 years of follow-up. PATIENTS AND METHODS: The NAR has been collecting data on total hip replacement (THR) since 1987. Reverse hybrid hip replacements were used mainly from 2000. We extracted data on reverse hybrid THR from this year onward until December 31, 2009, and compared the results with those from cemented implants over the same period. Specific cup/stem combinations involving 100 cases or more were selected. In addition, only combinations that were taken into use in 2005 or earlier were included. 3,963 operations in 3,630 patients were included. We used the Kaplan-Meier method and Cox regression analysis for estimation of prosthesis survival and relative risk of revision. The main endpoint was revision for any cause, but we also performed specific analyses on different reasons for revision. RESULTS: We found equal survival to that from cemented THR at 5 years (cemented: 97.0% (95% CI: 96.8-97.2); reverse hybrid: 96.7% (96.0-97.4)) and at 7 years (cemented: 96.0% (95.7-96.2); reverse hybrid: 95.6% (94.4-96.7)). Adjusted relative risk of revision of the reverse hybrids was 1.1 (0.9-1.4). In patients under 60 years of age, we found similar survival of the 2 groups at 5 and 7 years, with an adjusted relative risk of revision of reverse hybrids of 0.9 (0.6-1.3) compared to cemented implants. INTERPRETATION: With a follow-up of up to 10 years, reverse hybrid THRs performed well, and similarly to all-cemented THRs from the same time period. The reverse hybrid method might therefore be an alternative to all-cemented THR. Longer follow-up time is needed to evaluate whether reverse hybrid hip replacement has any advantages over all-cemented THR.

Direct comparison of polyethylene wear in cemented and uncemented acetabular cups.

BACKGROUND: It has been indicated that, in the long term, the rate of wear and the degree of osteolysis observed with uncemented acetabular components are greater than those associated with cemented cups, but most studies which compare the wear characteristics of cementless with cemented cups have used historical controls. We report a direct comparison of wear of a cemented and an uncemented cup with similar design, polyethylene, and sterilization method. MATERIALS AND METHODS: The study cohort includes 92 patients who were operated in 1997 with primary total hip replacement and have been followed for a period of 9-10 years. All patients were operated by posterolateral approach. In patients 70 years or older we used a cemented cup, in those 60 years or younger we used an uncemented cup, and in patients between 60 and 70 years we used either a cemented or uncemented cup as decided by the surgeon. At follow-up, radiographic imaging was obtained as standard anterioposterior view of the pelvis, and mean wear was determined as described by Livermore et al. RESULTS: The overall wear of the cemented acetabular components was 1.07 ± 0.78 mm, and that of the uncemented cups was 1.18 ± 0.61 mm (P = 0.529). Wear was significantly associated with male sex (P = 0.003), younger age (P = 0.003), and degree of inclination (P < 0.001), but wear was not significantly associated with cemented versus uncemented cup (P = 0.437). CONCLUSION: Our findings in this 9-10-year follow-up study suggest that cementless cups wear no more than cemented cups of similar design.

Dislocation after total hip arthroplasty with 28 and 32-mm femoral head.

BACKGROUND: Dislocation after primary total hip arthroplasty (THA) is a significant complication that occurs in 2-5% of patients. It has been postulated that increasing the femoral head diameter may reduce the risk of dislocation. The purpose of this paper is to report our experiences with a change from a 28 to a 32-mm femoral head. MATERIALS AND METHODS: The retrospective cohort study includes 2572 primary THA performed with a 28 or 32 mm diameter femoral head in the period February 2002 to July 2009. All patients were operated with a posterolateral approach, and all except 18 were operated because of osteoarthritis. Cemented stems were used in 1991 cases and uncemented stems in 581 cases. Cemented cups were used in 2,230 cases and uncemented cups in 342 cases. The patients have been routinely followed for 1-8 years in the 28-mm femoral head group and from 0.5-7.5 years in the 32 femoral head group. We defined a dislocation as an event in which the hip required reduction by a physician. RESULTS: Dislocation occurred in 49 hips with a 28-mm femoral head and in 4 hips with a 32-mm femoral head with an odds ratio of 6.06 (95% CI = 2.05-17.8) (P < 0.001). Otherwise, there were no significant associations between sex, age, diagnosis and type of prosthesis. CONCLUSIONS: Multivariate analyses of patients operated at our hospital indicate a significant association between femoral head diameter and dislocation after THA. There were no significant associations between dislocation and sex, age, diagnosis, or type of prosthesis.