The influence of osteoarthritis on the pattern of proximal femoral fractures

Hip osteoarthritis as a predictor of the fracture pattern in proximal femur fractures

INTRODUCTION

Several authors have suggested a correlation between the fracture patterns of proximal femur fractures and the degree of hip osteoarthritis (HOA), but the current evidence to support this are insufficient. The aim of our study was to demonstrate whether there is an association between the grade of HOA and fracture pattern observed, in patients presenting with a fragility fracture of the proximal femur.

MATERIALS AND METHODS

We contacted a retrospective review of all patients presenting to our institution with fragility fractures involving the proximal femur, between March 2012 and October 2013. Pathological fractures, high-energy injuries and patients with less than one year of follow-up were excluded from further analysis. Admission radiographs and severity of HOA were assessed according to Kellgren and Lawrence scale (minimal: Grades 1-2; severe: Grades 3-4). Fractures were classified according to AO/OTA classification.

RESULTS

A total of 1003 patients (725 females; 1003 fractures) met the inclusion criteria, having a mean age of 81.5 (46-106 years). With regards to fracture classification, 417 (41.6%) fractures were classified as extracapsular and 586 (58.4%) as intracapsular. A total of 939 (93.9%) patients presented with minimal HOA, whilst 61 (6.1%) of the patients presented with severe HOA. Of the 61 patients presenting with severe HOA, 42 patients (68.9%) sustained a 31A-interthrocanteric fracture and 19 patients (31.1%) sustained a 31B-intracapsular fracture. Regarding the patients presenting with minimal HOA (832 patients in total), 323 patients (38.8%) sustained 31A-intertrochanteric fracture and 509 patients (61.2%) sustained a 31B-intracapsular fracture. Patients presenting with severe HOA were found to have a statistically significant chance to present with an extracapsular fracture (p<0.01).

CONCLUSIONS

The degree of HOA is related to the fracture pattern in patients presenting following simple mechanical falls. More specifically, higher grades of HOA are associated with extracapsular fracture patterns, whereas lower grades of HOA are associated with intracapsular fracture patterns.

Differences in hip bone mineral density may explain the hip fracture pattern in osteoarthritic hips

INTRODUCTION

In patients with osteoarthritis of the hip (OAH), trochanteric fractures are much more common than femoral neck fractures. One reason may be altered bone composition in the proximal femurs. OAH often leads to a fixed external rotation of the hip, leading to difficulties in positioning during DXA measurements. We compared BMD in OAH-affected legs and healthy legs.

PATIENTS AND METHODS

40 patients with strictly unilateral OAH were cross-sectionally investigated with DXA at the hips and heels bilaterally as well as body composition of the legs. 3 regions of interest in the proximal femur were measured: femoral neck (FN), trochanter (TR), and total hip (TH). The design of the study allowed us to perform paired t-test between the OAH side and the healthy side.

RESULTS

BMD was increased by 4.1% in FN, and reduced by 8.3% in TR and 4.1% in TH (p < 0.001 for all comparisons).

INTERPRETATION

The differences in BMD, with decrease in the trochanter and increase in the femoral neck, may offer an explanation for the pattern of hip fractures seen in osteoarthritis. External rotation of the hip cannot explain the differences in BMD.

How do you know who needs prevention or treatment?

Osteoporosis is preventable with the various therapeutic options available today. It is therefore important to reach the patient who needs to be treated. If based only on clinical risk factors there is much room for therapeutic misassignation in both directions: too many and too few treatments. Generally speaking, only bone mass measurement can yield the correct risk for future fracture, and clinical factors taken alone might be misleading. Clinical factors can be used to modulate the therapeutic intervention based on assessment of bone mass. In very elderly people with several risk factors (poor vision, poor balance and awkward gait, use of psychotropic drugs, etc), bone mass measurements probably become less crucial in therapeutic decision, because factors other than bone mineral have also to be actively assessed. All in all, the use of cut offs of bone mineral density balanced with the clinical decision based on an individual examination, will allow assessment of the therapeutic level in a particular patient. A therapeutic intervention will never be an all or nothing phenomenon based on computerized data.