Summary

Hip chondral pathology of the femoral head is more prevalent but comparable in severity in diabetic patients compared to a matched control group, therefore diabetic patients should be counseled accordingly with respect to operative expectations.

Abstract

Introduction

Hip pain in patients with diabetes mellitus remains a challenge to diagnose and treat, and can be attributed to a variety of factors. Diabetes is clinically an important risk factor for cartilage degradation and osteoarthritis in the hip and knee joints. Few studies have reviewed the role of hip arthroscopy to diagnose and treat hip joint disease in the diabetic patient. We hypothesize that patients with diabetes and hip pain have greater degree of acetabular and femoral head chondromalacia at the time of hip arthroscopy compared to patients without diabetes.

Methods

In our institutional review board-approved study, we reviewed 791 consecutive hip arthroscopies performed by a single surgeon between 2010 and 2015. Patients under 18 years of age or who had previous ipsilateral hip surgery were excluded, leaving 321 patients who met inclusion criteria. Eleven diabetic patients were age-, sex- and BMI-matched to a control, non-diabetic cohort (n=310). Primary outcome variables were the acetabular and femoral head chondromalacia index (CMI), calculated as a product of the Outerbridge chondromalacia grade and surface area (mm2*severity).

Results

The diabetic and control groups were similar with respect to age (37.1 vs. 34.0, p=0.351), sex (64% female vs. 66% female, p=0.864), BMI (29.4 kg/m2 vs. 26.4 kg/m2, p=0.078), and operative side (64% right vs. 57% right, p=0.668). Both groups reported similar pain symptoms with respect to location; however a greater number of controls complained of radiculopathy (37% vs. 9%, p=0.013) while more diabetics complained of night pain (91% vs. 66%, p=0.023). On physical exam, diabetics had significantly less terminal hip flexion (83° vs. 92°, p=0.011) and internal rotation (0.5° vs. 6.4°, p<0.001) on the operative side compared to controls. Radiographic lateral center-edge angle (41° vs. 31°, p=0.025) and anterior center-edge angle (39° vs. 34°, p=0.038) were greater in diabetics than controls, consistent with hip overcoverage and pincer-type femoroacetabular impingement (FAI). MRI and intraoperative findings indicated that more diabetics demonstrated evidence of femoral head chondromalacia compared to controls (57% vs. 8%, p=0.05; 100% vs. 71%, p<0.001, respectively). The correlation between diabetes and femoral head chondromalacia was positive (r=0.281, p<0.001). Acetabular chondromalacia prevalence and grade were similar between the groups on operative findings. Acetabular (369 vs. 389, p=0.842) and femoral head CMI (510 vs. 354, p=0.081) did not vary significantly between diabetics and controls. Femoral head CMI positively correlated with acetabular CMI (r=0.398, p<0.001).

Discussion And Conclusion

Our results support our hypothesis that hip chondral pathology is more prevalent in diabetics compared to a similar cohort of non-diabetic patients. However, this difference did not translate to severity of the defect between the groups. Pre-clinical studies have demonstrated that elevated blood glucose levels adversely affect chondrocyte metabolism, leading to destruction of joint cartilage. The deficits in range of motion exhibited by diabetic patients may be due to pincer-type FAI but may also suggest soft tissue involvement about the hip joint. Further histological and molecular studies may better delineate the pathologic process that leads to hip pain in diabetic patients.