The Measurement And Clinical Significance Of Patellar Height Following Distal Femoral Replacement After Bone Tumor Resection

Background:Patellar height following endoprosthetic reconstruction can change as a result of anatomic,physiologic,and surgical reasons. The purpose of our study was to characterize the relationship between patellar height and the Musculoskeletal Tumor Society(MSTS) score, the motion degree of the knee, and anterior knee symptoms following distal femoral replacement after excision of bone tumors.Objectives:To study the diversification of patellar height following distal femoral replacement after bone tumor resection, and to explore its influence on postoperative knee function.Methods:Between January 2000 and December 2007,43 patients had been treated with prosthetic knee replacement after wide resection of primary malignant tumor of the distal part of the femur. We were able to obtain historical data, imaging studies, histologcal finding, and adequate personal fellow-up to determine the outcome for 30 patients. At the most recent follow-up examination, the standard lateral X-ray of knee was taken. The Musculoskeletal Tumor Society (MSTS) score was marked. The patellar height was measured by Insall-Salvati ratios. The motion degree of the knee was matched, and the anterior knee symptoms in the form of pain and/or a clicking sensation was recorded.Statistical analysis was done using SPSS software (version 15.0 for Windows). The data was expressed as mean±SD. Continuous data were evaluated with use of paired t tests. Categorical data were evaluated with use of square tests. Values of P<0.05 were considered to be statistically significant.Results:There were 14 males and 16 females in this group, with mean age 31.6(from 14 to 69). All the diagnoses were pathologically confirmed (17 patients with oseosarcoma,8 with giant cell tumor of bone,2 with chondrosarcoma,2 with leiomyosarcoma,1 with chondroblastoma). The fellow-up of all patients were 25 months to 120 months, averaged 49 months. There were no infection or skin necrosis after operation in these cases.The present group of patients were divided into 2 groups according to patellar position, one group with patella baja, and another group with normal patellar position, the MSTS score and range of motion were 20.1±4.4 points and 80.6°±24°in group with patella baja, the relative index in the group with normal patellar position were 24.6±3.6 points and 96.4°±16.5°, respectively. The MSTS score and The motion degree of the knee had significant deference (P<0.05) between tow groups. Eight patients reported anterior knee symptoms in the form of pain and/or a clicking sensation, there was no significant difference compared with cases without anterior knee symptoms according to patellar height.Conclusions:Patella baja is a more common complication after distal femoral resection and endoprosthetic reconstruction, which has a negative impact on knee function. In addition, there was no significant correlation between anterior knee symptoms and patellar height.