Eliminating impingement optimizes patellar biomechanics in high knee flexion / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>We investigated the impact of eliminating the impingement between extensor mechanism and tibial insert on patellar tracking and patellar ligament tension in high knee flexion.</p><p><b>METHODS</b>Six cadaveric specimens were tested on an Oxford-type testing rig. The Genesis II knee system was implanted into each specimen knee with the traditional tibial insert and high-flex insert successively. Compared to traditional insert, the high-flex insert was characterized with a chambered anterior post and a chambered anterior lip which eliminates patella-post and patellar ligament-anterior lip impingements. The patella was tracked with an NDI Optotrak Certus system. The patellar ligament tension was measured using a NKB S-type tension transducer.</p><p><b>RESULTS</b>There was a decrease of resultant patellar translation relative to the femur with statistically significant (P<0.05) at 90 degrees to 150 degrees of knee flexion and a decrease of patellar ligament tension with statistical significance (P<0.05) at 100 degrees, 120 degrees, 130 degrees, and 140 degrees of flexion using high-flex insert compared to traditional insert.</p><p><b>CONCLUSIONS</b>Eliminating the impingement between extensor mechanism and implant in high knee flexion altered patellar tracking and reduced patellar ligament tension, which would facilitate high knee flexion.</p>

Clinical results and peri-operative complications of total knee arthroplasty for patients with different ages / 中华外科杂志

<p><b>OBJECTIVE</b>To analyze the clinical results and complications of total knee arthroplasty (TKA) performed for patients with different ages.</p><p><b>METHODS</b>From January 2004 to March 2005,212 patients (300 knees) were followed up, all patients were divided into 6 groups according to the age. All the complications and knee society scores (KSS) were documented and retrieved for analysis.</p><p><b>RESULTS</b>KSS of all groups was significantly improved after TKA. The patients whose age was 70 years or older, and underwent bilateral TKA achieved the best improvement of knee function. The complication rate increased with the patients' age.</p><p><b>CONCLUSIONS</b>TKA predictably alleviates knee pain and restores knee function. Aging itself does not compromise clinical results of TKA. However perioperative complication rate is a little bit higher in aged patient group and simultaneously bilateral TKA patient group.</p>

Analysis of the failure mechanisms of the revision hip arthroplasties / 中华外科杂志

<p><b>OBJECTIVE</b>To investigate the failure mechanisms of revision hip arthroplasties and evaluate the effects of surgical technique, prosthesis design and patient-related risk factors on different failure mechanisms.</p><p><b>METHODS</b>A review of all revision hip arthroplasties from November 1995 to June 2008 identified 30 patients who underwent 30 revisions with 18 males and 12 females. The overall mean age for primary arthroplasties was 49 years (range 25-68 years) and 53 years (range 27-72 years) for index revision arthroplasties and the average interval between these two operations was 43.8 months (0-156 months). The failure mechanisms of index revision arthroplasties and primary arthroplasties were assessed and compared. Direct comparisons were made of data for the different age categories in terms of time to failures and reasons for failures.</p><p><b>RESULTS</b>Regarding revision or prosthesis removal as the end point of the study, the reasons for 30 revision arthroplasties were aseptic loosening in 22 hips (73.3%), infection in 4 hips (13.3%), periprosthetic fracture in 3 hips and instability in 1 hip (3.3%). The overall mean age for last arthroplasties or prosthesis removal was 58 years (range 38-77 years) with an average interval of 78.8 months (range 1-216 months) from previous revision arthroplasties. The mean time to failure for patients above 60 years of age was significantly shorter than patients below 60 years of age (P < 0.01).</p><p><b>CONCLUSION</b>The majority of failure mechanisms of revision hip arthroplasties are ineffective fixation of revisional implants and recurrence of local infection, which reveals the limitations to joint reconstruction philosophy and surgical technique.</p>

Reconstruction of the acetabular in the Crowe III dysplastic hip / 中华外科杂志

<p><b>OBJECTIVE</b>To investigate the method and the outcome of the acetabular reconstruction in the Crowe III dysplastic hip.</p><p><b>METHODS</b>From January 2001 to June 2007, 43 cases (54 hips) were diagnosed osteoarthritis secondary to Crowe III dysplastic hip. Total hip arthroplasty was performed in all cases. The Harris score was 39 pre-operation. The method of the acetabular reconstruction included acetabular deepening (group A), medial-wall osteotomy (group B), femoral head bone grafting (group C). Radiography data and Harris score were taken to evaluate the clinical outcome.</p><p><b>RESULTS</b>The method of the acetabular reconstruction included acetabular deepening in 27 cases (34 hips), medial-wall osteotomy in 12 cases (15 hips), femoral head bone grafting in 4 cases (5 hips). Forty cases were followed up by the mean time of 29 months. The bone union time of the osteotomy and bone grafting were 4 - 5 months postoperation. In the three groups the obliquity angle of the cup were (41.0 +/- 7.5) degrees , (46.0 +/- 7.7) degrees , (39.0 +/- 11.0) degrees ; the anteversion angle of the cup were (10.0 +/- 2.8) degrees , (9.0 +/- 2.5) degrees , (4.0 +/- 1.9) degrees ; the rotation center of the hip was shift superiorly (8.4 +/- 3.6) mm, (7.3 +/- 2.6) mm, (1.2 +/- 0.5) mm; the rotation center of the hip were shift internally (7.0 +/- 1.5) mm, (9.9 +/- 1.7) mm, (-2.7 +/- 1.2) mm, and the Harris score were 89, 91, 86 at the follow up. The complication included deep venous thrombosis in 2 cases, pulmonary embolism in 2 cases, sciatic nerve palsy in 4 cases.</p><p><b>CONCLUSION</b>Acetabular deepening, medial-wall osteotomy, femoral head bone grafting can be used in reconstruction of the acetabular in the Crowe III dysplastic hip.</p>