Delayed dislocation following metal-on-polyethylene hip replacement due to “silent” trunnion corrosion

AimsWe present a case series of ten metal-on-polyethylene total hip arthroplasties (MoP THAs) with delayed dislocation associated with unrecognised adverse local tissue reaction due to corrosion at the trunnion and pseudotumour formation.MethodsThe diagnosis was not suspected in nine of the ten patients (six female/four male; mean age 66 years), despite treatment in a specialist unit (mean time from index surgery to revision was 58 months, 36 to 84). It was identified at revision surgery and subsequently confirmed by histological examination of resected tissue. Pre-operative assessment and culture results ruled out infection. A variety of treatment strategies were used, including resection of the pseudotumour and efforts to avoid recurrent dislocation.ResultsThe rate of complications was high and included three deep infections, two patients with recurrent dislocation, and one recurrent pseudotumour.ConclusionThis series (mean follow-up of 76 months following index procedure and 19 months following revision THA) demonstrates that pseudotumour is an infrequent but important contributor to delayed instability following MoP THA. It is easy to overlook in the differential diagnosis, especially if the alignment of the components is less than optimal, leading to an assumption that malalignment is the cause of the dislocation. The instability is likely to be multifactorial and the revision surgery is complex. Take home message: Due to the high complication rate associated with revision in this cohort, the diagnosis should be borne in mind when counselling patients regarding the risks of revision surgery. Cite this article: Bone Joint J 2016;98-B:187–93.</jats:sec

Classifying health-related quality of life outcomes of total hip arthroplasty

Background. Primary total hip arthroplasty (THA) is an effective treatment for hip osteoarthritis, assessed by whatever distribution-based measures of responsiveness. Yet, the group level evaluation has provided very little evidence contributes to our understanding of the large variation of treatment outcome. The objective is to develop criteria that classify individual treatment health related quality of life (HRQOL) outcome after primary THA, adjusted by preoperative scores. Methods We prospectively measured 147 patients' disease specific HRQOL on the date of consultation and 12 months post operation by Western Ontario McMaster Universities Osteoarthritis Index (WOMAC). Regression models were used to determine the "expected" outcome for a certain individual baseline score. The ceiling effect of WOMAC measurement is addressed by implementing a left-censoring method. Results The classification criteria are chosen to be the lower boundary of the 95% confidence interval (CI) of the estimated median from the regression. The robustness of the classification criteria was demonstrated using the Monte-Carlo simulation. Conclusion The classification criteria are robust and can be applied in general orthopaedic research when the sample size is reasonable large (over 500).Medicine, Faculty ofOrthopaedics, Department ofNon UBCReviewedFacult

Classifying health-related quality of life outcomes of total hip arthroplasty

Abstract Background Primary total hip arthroplasty (THA) is an effective treatment for hip osteoarthritis, assessed by whatever distribution-based measures of responsiveness. Yet, the group level evaluation has provided very little evidence contributes to our understanding of the large variation of treatment outcome. The objective is to develop criteria that classify individual treatment health related quality of life (HRQOL) outcome after primary THA, adjusted by preoperative scores. Methods We prospectively measured 147 patients' disease specific HRQOL on the date of consultation and 12 months post operation by Western Ontario McMaster Universities Osteoarthritis Index (WOMAC). Regression models were used to determine the "expected" outcome for a certain individual baseline score. The ceiling effect of WOMAC measurement is addressed by implementing a left-censoring method. Results The classification criteria are chosen to be the lower boundary of the 95% confidence interval (CI) of the estimated median from the regression. The robustness of the classification criteria was demonstrated using the Monte-Carlo simulation. Conclusion The classification criteria are robust and can be applied in general orthopaedic research when the sample size is reasonable large (over 500).</p

Continued Good Results With Modular Trabecular Metal Augments for Acetabular Defects in Hip Arthroplasty at 7 to 11 Years

BACKGROUND: Reconstruction of large acetabular defects remains a substantial challenge in hip arthroplasty. There remains a paucity of data on the long-term results of acetabular trabecular metal augments. QUESTIONS/PURPOSES: The purpose of this study was to assess the survivorship, clinical outcomes, restoration of center of rotation of the hip, and radiological signs of component fixation of trabecular metal augments in the context of reconstruction of acetabular defects. METHODS: Between 2002 and 2005, we performed 56 revision (n = 53) and primary (n = 3) THAs using trabecular metal augments in combination with a trabecular metal acetabular component. Of the 56 patients, 16 (29%) died during followup. Of the 40 surviving patients, 37 (93%) had complete radiological followup, 23 (58%) had complete outcome questionnaire followup, and 17 (42%) provided partial questionnaire responses in the clinic or over the telephone. Median followup was 110 months (range, 88–128 months). During that period, we used these implants when preoperative templating indicated that an augment would be required to achieve acetabular implant stability with restoration of the hip center of rotation. We also chose during surgery to use an augment when we could not achieve a stable acetabular trial component without one. The combination of trabecular metal augments and trabecular metal shells was used in 18% (53 of 292) of our acetabular revisions during that time. Survivorship, functional outcome (WOMAC and Oxford hip score), health status (SF-12), and osseointegration according to the criteria of Moore and presence of radiolucencies were determined. RESULTS: Survivorship of the augments at 10 years was 92% (95% confidence interval, 81%–97%). Four patients underwent cup revision, one for infection and three for loosening. The mean WOMAC global score was 79 (SD 17), the mean Oxford hip score 76 (SD 18), the mean physical component SF-12 score was 39 (SD 11), and the mean mental component SF-12 score was 52 (SD 9). The center of rotation was corrected from more than 35 mm above the inter-teardrop line in 48 of 56 patients preoperatively to only five of 46 postoperatively. One patient had radiographic findings suggestive of loosening, but this patient was asymptomatic. CONCLUSIONS: The results of the acetabular trabecular metal augments continue to be encouraging in the medium to long term with low rates of revision or loosening in this complex group of patients. We continue to recommend the use of these augments in the reconstruction of complex acetabular defects. LEVEL OF EVIDENCE: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence

Methicillin-resistant Infection After Hip and Knee Replacement: Reason to Change Practice?

Infection after a primary total-joint replacement can be devastating. If the infecting organism is methicillin resistant, the chance of successful eradication of the infection is considerably decreased. What is more concerning is that these organisms are becoming increasingly common in periprosthetic joint infection. We have reviewed the literature and have outlined the effectiveness of single- and two-stage treatment regimens for this difficult problem. We have also looked at the screening and decolonisation methods that have been implemented in an attempt to decrease the risk of surgical site infections. Lastly, we outline our recommendations on how we should tackle this emerging and difficult problem that is affecting the orthopaedic world