Retrospective analysis of the clinical effect of secondary decompression after core decompression in the treatment of early and middle stage osteonecrosis of the femoral head(ONFH).

Thirty ONFH patients (50 hips) of the 307th Hospital of People′s Liberation Army, Anhui Medical University received core decompression, sequestrum erasion, impaction of bone filling particle from July 2008 to April 2013 were regarded as the single decompression group. Thirty ONFH patients (42 hips) of the 307th Hospital of People′s Liberation Army, Anhui Medical University obtained secondary decompression after single decompression from January 2010 to April 2013 were looked as the secondary decompression group. The necrosis stage was divided into the association research circulation osseous Ⅰstage or Ⅱstage. Harris hip score was used to evaluate the postoperative improvement of the hip function and the visual analogue scale (VAS) to assess the intensity of pain. The collapse and repair of lesions of the femoral head were detected based on the radiological datas (X-Ray, CT and MRI). The data between the two groups was compared by t test and Chi square test.

Sixty patients (92 hips) were all followed up, and the follow up-time was 25-84 months. At the time of 25 months after the operation, Harris hip scores in the two groups were significantly increased compared with preoperation, and there were signifficant differences between the two groups(P values were less than 0.05). The Harris hip score in the secondary decompression group [(91.21±3.32)points]was significantly higher than that in the single decompression group [(81.60±2.60)points], and the difference was statistically significant (t=-15.592, P<0.05). VAS scores were significantly reduced compared with preoperation in the two groups, and there were signifficant differences between the two groups(P values were less than 0.05). The VAS score in the secondary decompression group[(2.20±0.71)points] was significantly lower than that in the single decompression group [(3.27±1.51)points], and the difference was statistically significant (t=3.503, P=0.001). In the single decompression group, the excellent function was obtained in 2 hips, good function in 36 hips and fair function in 5 hips. The good rate was 76.0%, and the survival rate of the femoral head was 86.0%. In the secondary group, the excellent function was obtained in 35 hips, good function in 5 hips and fair function in 2 hips. The good rate was 95.2%, and the survival rate of the femoral head was 100.0%. There were signifficant differences in the good rate of the Harris hip score(χ²=6.548, P=0.011) and the survival rate of the femoral head (χ²=4.529, P=0.033). The femoral head repaired completely in the 37 hips of excellent function, 6 hips repaired incompletely among the 41 hips of good function, but did not appear fracture. Seven hips of fair function appeared narrowing of joint space and subchondral fracture, and 3 hips were cured by total hip arthroplasty.

Secondary decompression after core decompression can induce the process of wound repair in femoral head again, further improve the hip function, alleviate the pain, and play a good therapeutic on hip joint.