Hip resurfacing remains a potentially valuable surgical procedure for appropriately-selected patients with optimised implant choices. However, concern regarding high early failure rates continues to undermine confidence in use. A large contributor to failure is adverse local tissue reactions around metal-on-metal (MoM) bearing surfaces. Such phenomena have been well-explored around MoM total hip arthroplasties, but comparable data in equivalent hip resurfacing procedures is lacking. In order to define genetic predisposition, we performed a case-control study investigating the role of human leucocyte antigen (HLA) genotype in the development of pseudotumours around MoM hip resurfacings. A matched case-control study was performed using the prospectively-collected database at the host institution. In all, 16 MoM hip resurfacing 'cases' were identified as having symptomatic periprosthetic pseudotumours on preoperative metal artefact reduction sequence (MARS) MRI, and were subsequently histologically confirmed as high-grade aseptic lymphocyte-dominated vasculitis-associated lesions (ALVALs) at revision surgery. ‘Controls’ were matched by implant type in the absence of evidence of pseudotumour. Blood samples from all cases and controls were collected prospectively for high resolution genetic a nalysis targeting 11 separate HLA loci. Statistical significance was set at 0.10 a priori to determine the association between HLA genotype and pseudotumour formation, given the small sample size.Aims
Methods
Hip resurfacing may be a useful surgical procedure when patient selection is correct and only implants with superior performance are used. In order to establish a body of evidence in relation to hip resurfacing, pseudotumour formation and its genetic predisposition, we performed a case-control study investigating the role of HLA genotype in the development of pseudotumour around MoM hip resurfacings. All metal-on-metal (MoM) hip resurfacings performed in the history of the institution were assessed. A total of 392 hip resurfacings were performed by 12 surgeons between February 1st 2005 and October 31st 2007. In all cases, pseudotumour was confirmed in the preoperative setting on Metal Artefact Reduction Sequencing (MARS) MRI. Controls were matched by implant (ASR or BHR) and absence of pseudotumour was confirmed on MRI. Blood samples from all cases and controls underwent genetic analysis using Next Generation Sequencing (NGS) assessing for the following alleles of 11 HLA loci (A, B, C, DRB1, DRB3/4/5, DQA1, DQB1, DPB1, DPA1). Statistical significance was determined using a Fisher's exact test or Chi-Squared test given the small sample size to quantify the clinical association between HLA genotype and the need for revision surgery due to pseudotumour. Both groups were matched for implant type (55% ASR, 45% BHR in both the case and control groups). According to the ALVAL histological classification described by Kurmis et al., the majority of cases (63%, n=10) were found to have group 2 histological findings. Four cases (25%) had group 3 histological findings and 2 (12%) patients had group 4 findings. Of the 11 HLA loci analysed, 2 were significantly associated with a higher risk of pseudotumour formation (DQB1*05:03:01 and DRB1*14:54:01) and 4 were noted to be protective against pseudotumour formation (DQA1*03:01:01, DRB1*04:04:01, C*01:02:01, B*27:05:02). These findings further develop the knowledge base around specific HLA genotypes and their role in the development of pseudotumour formation in MoM hip resurfacing. Specifically, the two alleles at higher risk of pseudotumour formation (DQB1*05:03:01 and DRB1*14:54:01) in MoM hip resurfacing should be noted, particularly as patient-specific genotype-dependent surgical treatments continue to develop in the future.
Proponents of quadriceps-sparing (QS) subvastus approach for total knee arthroplasty (TKA) suggest short-term advantages including better early functional results, less pain and shorter hospital stay. However, because of potentially reduced visibility and exposure, the QS approach may compromise component alignment – an important surgeon-controlled outcome affecting implant longevity. The purpose of this study was to determine if a QS approach resulted in compromised component alignment compared to a medial parapatellar arthrotomy (MPPA), when both were performed with contemporary minimally invasive surgery (MIS) principles including small incision (≤ 15 cm), MIS instrumentation, patellar subluxation without eversion, and in situ bone cuts. This prospective, randomized, double-blinded study enrolled 128 patients with knee osteoarthritis undergoing primary TKA using the same cemented, posterior-stabilized prosthesis. After skin incision, patients were randomized to MPPA (n = 66) or QS technique (n = 62), with all surgeries performed by two fellowship-trained arthroplasty surgeons. Using the Knee Society roentgenographic evaluation system, two reviewers blinded to the surgical approach evaluated post-operative radiographs to measure coronal and sagittal plane alignment using the standing femoral and tibial angles as well as the lateral femoral flexion and tibial angles. Inter-observer agreement was ensured by a secondary review of all x-rays where the two observers differed by more than 1 degree in their measurements of a specific radiograph. Differences in mean angles were evaluated using the general linear model and differences in proportions were evaluated using binary regression. All analyses were conducted with SAS 9.3 on the Windows Ultimate 64-bit operating system.Introduction:
Methods:
Clinical trials have generally failed to demonstrate superior clinical effectiveness of minimally invasive surgical approaches for total knee arthroplasty (TKA). The hypothesis of the current study was that avoiding incision of the quadriceps tendon would result in a significantly faster recovery of ambulatory function after total knee arthroplasty, compared to a technique that incised the quadriceps tendon. The MIKRO (Minimally Invasive Knee Replacement Outcomes) Study is a prospective, level 1 RCT that enrolled 128 patients with knee osteoarthritis who had failed non-operative treatment, and had decided to proceed with TKA. After skin incision, 64 patients each were randomized to either a subvastus (SV) or medial parapatellar arthrotomy (MPPA) approach. All surgeries were done with the same TKA implant, with anesthesia, post-operative analgesia, and physical therapy standardized for both groups. A Patient Diary methodology was used as the primary outcome measure for ambulatory function. During the first 8 weeks after TKA, a research assistant blinded to treatment assignment telephoned each patient and completed study forms that documented indoor and outdoor walking relative to use of ambulatory devices, as well as Knee Society Score (KSS) and the UCLA activity scale. The UCLA score and change in KSS from baseline at 4- and 12-week follow-up were used to begin the validation process for an Ambulatory Function Score (AFS) derived from diary indoor and outdoor scores.INTRODUCTION
METHODOLOGY
