Patient-specific instrumentation improved three-dimensional accuracy in total knee arthroplasty: a comparative radiographic analysis of 1257 total knee arthroplasties.

BACKGROUND: The purpose of this study was to compare restoration of mechanical limb alignment and three-dimensional component-positioning between conventional and patient-specific instrumentation in total knee arthroplasty. METHODS: Radiographic data of patients undergoing mobile-bearing total knee arthroplasty (n = 1257), using either conventional (n = 442) or patient-specific instrumentation (n = 812), were analyzed. To evaluate accuracy of axis restoration and 3D-component-positioning between conventional and patient-specific instrumentation, absolute deviations from the targeted neutral mechanical limb alignment and planned implant positions were determined. Measurements were performed on standardized coronal long-leg and sagittal knee radiographs. CT-scans were evaluated for accuracy of axial femoral implant rotation. Outliers were defined as deviations from the targeted neutral mechanical axis of > ± 3° or from the intraoperative component-positioning goals of > ± 2°. Deviations greater than ± 5° from set targets were considered to be severe outliers. RESULTS: Deviations from a neutral mechanical axis (conventional instrumentation: 2.3°± 1.7° vs. patient-specific instrumentation: 1.7°± 1.2°; p < 0.001) and numbers of outliers (conventional instrumentation: 25.8% vs. patient-specific instrumentation: 10.1%; p < 0.001) were significantly lower in the patient-specific instrumentation group. Significantly lower mean deviations and less outliers were detected regarding 3D-component-positioning in the patient-specific instrumentation compared to the conventional instrumentation group (all p < 0.05). CONCLUSIONS: Patient-specific instrumentation prevented from severe limb malalignment and component-positioning outliers (> ± 5° deviation). Use of patient-specific instrumentation proved to be superior to conventional instrumentation in achieving more accurate limb alignment and 3D-component positioning, particularly regarding femoral component rotation. Furthermore, the use of patient-specific instrumentation successfully prevented severe (> 5° deviation) outliers.

Patient-specific instrumentation improved mechanical alignment, while early clinical outcome was comparable to conventional instrumentation in TKA.

PURPOSE: The aim of this prospective study was to compare early clinical outcome, radiological limb alignment, and three-dimensional (3D)-component positioning between conventional and computed tomography (CT)-based patient-specific instrumentation (PSI) in primary mobile-bearing total knee arthroplasty (TKA). METHODS: Two hundred ninety consecutive patients (300 knees) with severe, debilitating osteoarthritis scheduled for TKA were included in this study using either conventional instrumentation (CVI, n = 150) or PSI (n = 150). Patients were clinically assessed before and 2 years after surgery according to the Knee-Society-Score (KSS) and the visual-analog-scale for pain (VAS). Additionally, the Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) and the Oxford-Knee-Score (OKS) were collected at follow-up. To evaluate accuracy of CVI and PSI, hip-knee-ankle angle (HKA) and 3D-component positioning were assessed on postoperative radiographs and CT. RESULTS: Data of 222 knees (CVI: n = 108, PSI: n = 114) were available for analysis after a mean follow-up of 28.6 ± 5.2 months. At the early follow-up, clinical outcome (KSS, VAS, WOMAC, OKS) was comparable between the two groups. Mean HKA-deviation from the targeted neutral mechanical axis (CVI: 2.2° ± 1.7°; PSI: 1.5° ± 1.4°; p < 0.001), rates of outliers (CVI: 22.2%; PSI: 9.6%; p = 0.016), and 3D-component positioning outliers were significantly lower in the PSI group. Non-outliers (HKA: 180° ± 3°) showed better clinical results than outliers at the 2-year follow-up. CONCLUSIONS: CT-based PSI compared with CVI improves accuracy of mechanical alignment restoration and 3D-component positioning in primary TKA. While clinical outcome was comparable between the two instrumentation groups at early follow-up, significantly inferior outcome was detected in the subgroup of HKA-outliers. LEVEL OF EVIDENCE: Prospective comparative study, Level II.

Chondrosarcoma of the hand: is a wide surgical resection necessary?

Chondrosarcomas of the hand are rare and generally treated with surgical resection. Thirteen patients with Grade 1 chondrosarcoma of the small bones of the hand were followed up for a mean of 99.8 months (range, 26-293 months). In eight patients (Group 1) curettage and reconstruction with cancellous bone was done and in five patients (Group 2) a wide resection was done. No patient experienced relapse in Group 2. In Group 1 one patient had a local relapse 18 months after intralesional resection. Using the Musculoskeletal Tumor Society score for evaluation, the clinical results showed an average of 98% and 95% of the normal function in Groups 1 and 2, respectively. None of the patients had evidence of systemic spread of the disease. With a relapse rate of 12.5% and no distant metastases after curettage, intralesional resection is the preferred method of treatment in Grade 1 chondrosarcoma of the hand, allowing the patient to avoid amputation and major loss of function.

Radiation synovectomy with (166)Ho-ferric hydroxide: a first experience.

UNLABELLED: Radiation synovectomy (RS) is indicated when conventional pharmacologic treatment of chronic synovitis has not relieved its symptoms. The use of radionuclides that are bound to ferric hydroxide (FH) particles has been shown to be effective and safe for this procedure. (166)Ho-FH macroaggregates offer promising properties for RS but there is a lack of clinical data. We investigated the efficacy and safety of (166)Ho-FH in a prospective clinical trial in patients suffering from chronic synovitis. METHODS: Twenty-four intraarticular injections were performed in 22 patients receiving a mean activity of 1.11 GBq (range, 0.77-1.24 GBq) (166)Ho-FH. Blood activity measurements and monitoring of activity distribution were performed by whole-body gamma-camera imaging for control of leakage 3 and 24 h after injection of (166)Ho-FH. The patients were evaluated clinically before RS, 1 wk and 1 mo after the treatment, and thereafter in 3-mo intervals by assessing joint effusion, pannus, local pain, range of motion, and the patient's satisfaction. RESULTS: In 18 of 24 treatments, no leakage to nontarget organs was visible, whereas small amounts of activity could be detected in the local inguinal lymph nodes in 6 patients and to the lungs and to the liver in 1 patient (<0.1%). In all cases leakage to the lymph nodes was <1%. Leakage to the blood was negligible. Clinically, 17 patients (71%) exhibited a complete or partial response. CONCLUSION: RS with (166)Ho-FH was safe and effective in patients with chronic synovitis of different origin. Controlled clinical trials are necessary to evaluate the therapeutic efficacy and safety compared with the treatment with other radionuclides and glucocorticosteroids.

Reconstruction of the pelvis after tumor resection in children and adolescents.

Thirty patients younger than 19 years with malignant bone tumors of the pelvis were treated by limb salvage surgery between 1970 and 1998. Functional and oncologic results were reviewed retrospectively. In 10 patients the defect was reconstructed by an endoprosthesis and in 20 patients reconstruction by autologous grafts (n = 7), allograft and prosthesis combinations (n = 2), bone cement reconstruction (n = 1), iliosacral arthrodesis (n = 1), modified Girdlestone procedure (n = 3), or resection without reconstruction (n = 6) was done. Three and one-half reoperations per patient were necessary postoperatively after allograft reconstruction, 2.5 reoperations per patient were necessary after endoprosthetic reconstruction, and 0.8 reoperations per patient were necessary after other or no reconstruction. After a mean followup of 52 months (range, 2-241 months), 17 patients were alive, 15 of whom were continuously disease-free, and 13 patients had died of their disease. Functional ratings were 81% after autograft, 73% after allograft, and 60% after endoprosthetic reconstruction. Defect reconstruction varied according to the type of resection. Type I resections were best reconstructed by biologic methods. Endoprosthetic reconstruction after periacetabular resection with the advantage of preservation of a functional hip and body integrity was associated with a high rate of complications and reoperations. Its role compared with allograft reconstruction, modified Girdlestone procedure, or no reconstruction requires additional investigation.