Clinical outcomes and impact factors of hip preserving surgery for osteonecrosis of the femoral head based on China-Japan Friendship Hospital classification

Lihua LIU; Wei SUN; Fuqiang GAO; Liming CHENG; Zirong LI; Jiangning WANG

ABSTRACT

Objective:

To evaluate the risk factors related to the mid-term outcomes of hip preserving surgery for early stages osteonecrosis of the femoral head (ONFH) basing on China-Japan Friendship Hospital (CJFH) classification system.

Methods:

From June 2012 to September 2016, there were consecutive 325 patients (432 hips) were enrolled and divided into different preserving surgery groups, namely core decompression (CD) group 141 hips and "lightbulb" operation (LB) group 291 hips, respectively. Harris hip score (HHS) was used to evaluate the clinical outcomes. The progression of ONFH was observed by radiography. Clinical failure was defined as worsen of HHS and/or radiographic evaluation. Clinical endpoint events were marked as significant hip pain (HHS<70), and/or collapse of the femoral head requiring further interventions. Potential risk factors, including sex, age, etiology, the duration from symptom onset to treatment, preoperative CJFH type, ARCO stage and HHS, were analyzed using univariate risk analysis and Cox regression multivariate risk model.

Results:

The rate of hip failure was 47.5% (67/141) in CD group, including type C+M 13.0% (3/23), L1 38.1% (24/63), L2 82.4% (14/17) and L3 68.4% (26/38), respectively. There was significant difference in age (χ 2=3.887, P=0.049), type of CJFH (χ 2=40.943, P=0.000) in CD group. The Cox regression analysis revealed that age≥40 ( HR=2.325, 95% CI 1.398, 3.866, P=0.000), pre-HHS 70-80 ( HR=2.163, 95% CI 1.140, 4.105, P=0.018) and <70 ( HR=2.597, 95% CI 1.173, 5.749, P=0.019), type L2 ( HR=35.052, 95% CI 7.721, 159.133, P=0.000) and L3 ( HR=13.242, 95% CI 3.104, 56.491, P=0.000) were associated with failure of core decompression. The rate of hip failure was 36.4%(106/291) in LB group, including type C+M 33.3% (1/3), L1 31.3% (41/131), L2 84.6% (22/26) and L3 32.1% (42/131), respectively. There were significant differences in age (χ 2=8.437, P=0.004), pre-HHS (χ 2=19.737, P=0.000) and type of CJFH (χ 2=29.265, P=0.000) in LB group. The Cox regression analysis showed that poor pre-HHS ( HR=5.102, 95% CI 2.339, 11.129, P=0.000), type L2 ( HR=32.761, 95% CI 6.165, 43.507, P=0.000) were associated with failure of "lightbulb" preserving surgery.

Conclusion:

The results of hip preserving surgery for ONFH are associated with age, preoperative HHS and CJFH typing. The prognosis depends on the severity of symptoms, the residual of weight-bearing joint surface and lateral pillar of the femoral head.