Purpose To report the early clinical and radiographic outcomes of custom total knee arthroplasty (TKA) in knees that had prior osteotomies and/or extra-articular fracture sequelae. Methods The authors retrospectively analysed a consecutive series of 444 knees that received custom TKA between 2016 and 2019 and identiied 41 knees that had prior extra-articular events (osteotomies or fracture sequelae). Patients responded to pre-and post-operative (> 12 months) questionnaires, including Knee Society Score (KSS), Oxford Knee Score (OKS), Forgotten Joint Score (FJS) and Knee injury and Osteoarthritis Outcome Score (KOOS). Net improvements were calculated by subtracting pre-from post-operative scores. In addition to a preoperative CT scan, pre-and post-operative long-leg weightbearing radiographs were obtained, on which the hip-knee-ankle (HKA) angle, femoral mechanical angle (FMA, between femoral mechanical axis and joint line) and tibial mechanical angle (TMA, between tibial mechanical axis and joint line) angles were measured, and alignment was planned within a 'target zone' of FMA and TMA within 85°-95° and HKA angle within 175°-183°. Agreements between preoperative, planned and post-operative angles were calculated using intra-class correlation coeicients (ICC). Results From the initial 41 knees, 3 had incomplete post-operative data and 1 was revised for painful stifness due to uncorrected rotational malunion, leaving 37 knees for analysis. Twenty had prior osteotomies (tibia, n = 18, femur, n = 2), 8 had isolated fractures (tibial, n = 3; femoral, n = 5), and 9 had both osteotomies and fractures. Postoperative coronal alignments were 90.4° ± 2.4° for FMA, 89.3° ± 2.6° for TMA and 179.9° ± 3.0° for HKA angle. Agreements between planned and achieved alignments were fair to excellent, and 29 (78%) knees were within the 'target zone'. At a mean follow-up of 15 ± 5 months, all clinical scores had improved signiicantly (p < 0.001). Conclusions Custom TKA granted satisfactory clinical outcomes and a low complication rate in knees that had prior osteotomies and/or extra-articular fracture sequelae. Using custom implants and strategies for coronal alignment, 29 (78%) of the 37 knees were successfully aligned within the 'target zone', and 35 (95%) of the 41 knees did not require ligament release. Level of evidence IV.
Background: Acetabular revision with extra-large (jumbo) cementless cups is an effective treatment for many cavitary and segmental peripheral bone defects. However, hip center elevation may occur with the use of a jumbo cup owing to the superior direction of reaming and the increased diameter of the component compared with the native acetabulum. Purposes: The primary goal of this study was to evaluate the radiographically observed hip center elevation with the use of jumbo cups in acetabular and total hip revision at our institution. Materials and methods: We retrospectively reviewed control radiographic images of 43 consecutive patients treated with acetabular and total hip revision arthroplasty with a press-fit cementless cup. The difference between the height of the rotation center of the acetabular cup and the height of the rotation center of the contralateral native hip relative to the inter teardrop line was radiographically measured. Results: The radiographically measured mean elevation of the rotation center of the jumbo cup was 8,75 mm, which yielded an average increase in the height of the rotation centre of 83,6. A mean vertical shift of the rotation center of 0,72 mm was estimated for every 1 mm increase in the size of the jumbo cup. Conclusions: Our results indicate that the use of jumbo cups in revision hip arthroplasty leads to elevation of the rotation center of the hip with an average of 9 mm. This could be considered by the surgeon in an attempt to restore leg length, stability and biomechanics of the prosthetic hip.
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