Nianfei Zhang

Steroid-induced osteonecrosis THE NUMBER OF LESIONS IS RELATED TO THE DOSAGE

Severe acute respiratory syndrome (SARS) is a newly described infectious disease caused by the SARS coronavirus which attacks the immune system and pulmonary epithelium. It is treated with regular high doses of corticosteroids. Our aim was to determine the relationship between the dosage of steroids and the number and distribution of osteonecrotic lesions in patients treated with steroids during the SARS epidemic in Beijing, China in 2003. We identified 114 patients for inclusion in the study. Of these, 43 with osteonecrosis received a significantly higher cumulative and peak methylprednisolone-equivalent dose than 71 patients with no osteonecrosis identified by MRI. We confirmed that the number of osteonecrotic lesions was directly related to the dosage of steroids and that a very high dose, a peak dose of more than 200 mg or a cumulative methylprednisolone-equivalent dose of more than 4000 mg, is a significant risk factor for multifocal osteonecrosis with both epiphyseal and diaphyseal lesions. Patients with diaphyseal osteonecrosis received a significantly higher cumulative methylprednisolone-equivalent dose than those with epiphyseal osteonecrosis. Multifocal osteonecrosis should be suspected if a patient is diagnosed with osteonecrosis in the shaft of a long bone.

The learning curve for minimally invasive Oxford phase 3 unicompartmental knee arthroplasty: cumulative summation test for learning curve (LC-CUSUM)

BackgroundThe minimally invasive Oxford unicompartmental knee arthroplasty (UKA) is a demanding procedure but has many advantages compared with total knee arthroplasty (TKA). The aim of this observational study was to investigate the learning curve of one experienced surgeon introducing minimally invasive Oxford phase 3 UKA into his routine clinical practice.MethodsThe first 50 consecutive cases of minimally invasive Oxford phase 3 UKA performed by one surgeon were evaluated to determine whether there was an association between outcomes and the cumulative number of cases performed, indicating the presence of learning curve. The cohort was divided into two groups: group A comprised the first 25 cases and group B cases 26–50. Duration of surgery, blood loss, Hospital for Special Surgery score, range of motion, complications, and the radiographical position of the implant were compared between the groups. The cumulative summation test for learning curve (LC-CUSUM) was then used to further analyze the learning curve.ResultsThe mean age and follow-up were 64.4 years and 50.9 months, respectively. The duration of surgery and blood loss were significantly more favorable in group B. The length of incision gradually reduced from 9.7 ± 1.3 to 8.5 ± 1.1 cm. Failures were identified in nine patients (18%). Two revisions and two dislocations were encountered in group A; one revision was performed 4 years after surgery for a patient in group B because of a fracture. One case of lateral compartment osteoarthritis was identified in group A. Two patients in each group reported continuing unexplained pains. CUSUM analysis showed that failure rates diminished rapidly after 16 cases and reached an acceptable rate after 29 cases.ConclusionsMinimally invasive Oxford phase 3 UKA for anteromedial osteoarthritis is a demanding procedure, but satisfactory outcomes can be achieved after approximately 25 cases.

Clinical diagnosis and arthroscopic treatment of acetabular labral tears

Objective:  To investigate the clinical diagnosis and arthroscopic treatment of acetabular labral tears.

Minimally invasive unicompartmental knee arthroplasty for spontaneous osteonecrosis of the knee.

To explore the outcome and surgical technique of minimally invasive unicompartmental knee arthroplasty (UKA) for spontaneous osteonecrosis of the knee.

Treatment of osteonecrosis of femoral head with modified lightbulb operation: A 10-year follow-up study

Objective: To retrospectively analyze the clinical efficacy of a modified light bulb operation for the treatment of femoral head osteonecrosis. Methods: A total of 38 patients (59 hips) were treated with this procedure between June 2004 and June 2005, and were followed up for over 10 years. They were classified into ARCO stage II (23 hips), stage IIIa (29 hips) and stage IIIb (7 hips); and into the China- Japan Friendship Hospital (CJFH) type C (3 hips), type L1 (7 hips), type L2 (19 hips) and type L3 (30 hips). In the operation, a bone window was made at the femoral head-neck junction. Autologous cancellous bone harvested around the window was mixed with recombinant human bone morphogenetic protein-2 (rh-BMP2), implanted to the subchondral bone and impacted. The cavity was filled with tricalcium phosphate porous bioceramic (Bio- TCP). The Harris hip score was used to evaluate the postoperative improvement of hip function. Excellent, good, fair, and poor results were defined as Harris hip scores of 90-100, 80-89, 70-79 and below 70, respectively. Harris hip scores ＞ 70 were defined as clinical successful. The radiographic follow-up was evaluated by X-ray and CT scan before and 3, 6, 12 months and every year after the treatment. No presences of collapse, crescent sign or narrower joint space were defined as radiographic successful results. Results: Six patients (9 hips) were lost in the follow-up. Of the rest, excellent, good, fair and poor functions were obtained in 30, 6, 5 and 9 hips, respectively. All the failed cases had total hip replacement. The average preoperative Harris hip score of all hips was 60.2 points. The average postoperative Harris hip score was 87.3 points at 10 years after the surgery, with an increase of 27.1 points (p ＜ 0.001). The radiological results were successful in 76% of the hips with preserved spherity of the femoral head and incorporation of the grafts in the femoral heads could be found. Conclusion: (1) The modified lightbulb operation used local cancellous grafts from the femoral head and expanded its volume with Bio-TCP and rhBMP-2. An overall 82% clinical successful rate and 76% radiographic successful rate was achieved with a mean follow-up of 10 years. (2) The operation did not need other autologous grafts to avoid donor site morbidity and was technically easy to perform. Grafts supporting to the lateral column in the necrotic area were found to be the most important determinant to prevent subsequent collapse of the femoral head.