The Effects of Patient Factors on the Functions and Clinical Results of Unicompartmental Knee Arthroplasty Using an Oxford Mobile Bearing Prosthesis

PURPOSE: The purpose of this study was to determine whether the functions and longevity of unicompartmental knee arthroplasty (UKA) are influenced by such patient factors as gender, age, height, weight and the body mass index (BMI) based on a comparative study of the cases. MATERIALS AND METHOD: Among the patients who underwent a UKA using an Oxford(R) phase 3 prosthesis, 154 cases (male: 13 cases, female: 141 cases) were categorized into two groups by their gender, age, height, weight and BMI, and they were followed-up for at least 5 years after operation. Their mean age, height, weight and BMI were 61.6 years, 154.5 cm, 61.9 kg and 25.9 kg/m2, respectively, and the mean follow-up period was 6 years 7 months. Clinical assessments were done using the Knee Society Score rating system. RESULTS: The average knee and function scores improved from 55.9 and 54.9 preoperatively to 87.9 and 82.4 at the last follow-up, respectively, and the mean range of knee motion improved from 129.7degrees to 133.5degrees. The postoperative knee score, function score and range of knee motion improved significantly in all the groups. The group younger than 60 years old had better function scores preoperatively and the group of taller than 155 cm had a larger range of knee motion postoperatively, but there were no other significant difference. The cumulative survival rate of the implant was 93.3%, and there was no significant difference of the survival rate of the implant according to gender, age, height, weight, and BMI. CONCLUSION: The clinical results of UKA were satisfactory in all the groups regardless of gender, age, height, weight and BMI with a mean of 6 years 7 months follow-up, and there were no significant differences on comparison between each group. Therefore, the mid-term clinical results of UKA using an Oxford phase 3 prosthesis are not influenced by these patient factors.

The Influence of Symtomless Degenerative Changes of the Patellofemoral Joint on Clinical Results of Medial Unicompartmental Knee Arthroplasty / 대한정형외과학회잡지

PURPOSE: To evaluate the influence of degenerative changes in the patellofemoral joint on the clinical results of medial unicompartmental knee arthroplasty (UKA). MATERIALS AND METHODS: Between January and December 2002, we operated on 180 cases of minimally invasive UKA using the Oxford(R) phase 3. Of the 180 cases, 156 were followed up for a minimum period of 5 years. Based on intraoperative degenerative findings of the patellofemoral joint, we classified cases into 4 groups (Group I-78 cases, Group II-40 cases, Group III-27 cases, Group IV-11 cases), and the clinical data were analyzed prospectively. RESULTS: During follow-up, which averaged 6 years and 2 months, the knee score, the knee function score, the range of knee motion and the tibiofemoral angle were improved significantly (p0.05). To date, no complication or failure involving the patellofemoral joint has been observed. CONCLUSION: Clinical results of UKA are satisfactory for all groups, and the severity of patellofemoral degeneration has no influence on clinical outcome. Symptomless degenerative arthritis of the patellofemoral joint is not a contraindication for medial UKA.

Causes and Treatments of the Early Failure after Unicompartmental Knee Arthroplasty

PURPOSE: We wanted to evaluate the causes, treatments and preventive measures for early failure of unicompartmental knee arthroplasty (UKA) by performing an analysis of the cases. MATERIALS AND METHODS: We retrospectively analyzed 687 cases of UKA that had been performed from January 2002 to December 2006. There are 622 cases of the meniscal bearing type, 31 cases of the tracked bearing type and 34 cases of the fixed bearing type. All of the cases were performed by minimally invasive surgery. RESULTS: Early failures after UKA were seen in 36 cases, and these failures occurred from 4 months postoperatively to 5 years 7 months postoperatively. There were 20 mobile bearing dislocations, 18 femoral or tibial component loosenings, 4 infections, 1 medial tibial condylar fracture and 1 case of pain of unknown origin. The most common cause of the failed cases of the meniscal bearing type was bearing dislocation. All of the failed cases of the tracked and fixed types were from loosening of the component. Simple dislocations of bearing were treated by bearing change. All of the other cases were treated with revision TKA or UKA. CONCLUSION: Selection of an appropriate prosthesis and accurate surgical technique are needed to improve the clinical results and reduce failures. Open bearing change can be done for the cases of simple bearing dislocation, and revision TKA is needed if this is accompanied by other complications.

The Surgical Treatment for Spinal Intradural Extramedullary Tumors

BACKGROUND: We wanted to investigate the results of surgical treatment and analyze the factors that have an influence on the neurologic symptoms and prognosis of spinal intradural extramedullary (IDEM) tumors. METHODS: The spinal IDEM tumor patients (11 cases) who had been treated by surgical excision and who were followed up more than 1 year were retrospectively analyzed. Pain was evaluated by the visual analogue scale (VAS) and the neurologic function was assessed by Nurick's grade. The pathological diagnosis, the preoperative symptom duration, the tumor location on the sagittal and axial planes and the percentage of tumor occupying the intradural space were investigated. In addition, all these factors were analyzed in relation to the degree of the preoperative symptoms and the prognosis. On the last follow-up, the MRI was checked to evaluate whether or not the tumor had recurred. RESULTS: The most common diagnosis was schwannomas (73%), followed by meningiomas (18%). The percentage of tumor occupying the intradural space was 82.9 +/- 9.4%. The VAS score was reduced in all cases from 8.0 +/- 1.2 to 1.2 +/- 0.8 (p = 0.003) and the Nurick's grade was improved in all cases from 3.0 +/- 1.3 to 1.0 +/- 0.0 (p = 0.005). The preoperative symptoms were correlated with only the percentage of tumor occupying the intradural space (VAS; r2 = 0.75, p = 0.010, Nurick's grade; r2 = 0.69, p = 0.019). One case of schwannoma recurred. CONCLUSIONS: The degree of neurologic symptoms was correlated with the percentage of tumor occupying the intradural space. All the tumors were able to be excised through the posterior approach. The postoperative neurologic recovery was excellent in all the cases regardless of any condition. Therefore, aggressive surgical excision is recommended even for cases with a long duration of symptoms or a severe neurologic deficit.