Stress fracture of os ischium

Case report: ischial stress fracture non-union in a college football player

Stress fractures are common injuries associated with repetitive high-impact activities, often in high-level athletes and military recruits. Although predominantly occurring in the lower extremities, stress fractures may occur wherever there is a sudden increase in frequency or intensity of activity, thereby overloading the yield point of the local bone environment. Ischial stress fractures are a rarely diagnosed cause of pain around the hip and pelvis. Often, patients present with buttock pain with activity, which can be misdiagnosed as proximal hamstring tendonitis or avulsion. Here, we report a case of a college football player who was diagnosed with an ischial stress fracture which went on to symptomatic non-union after extensive conservative management. We treated his ischial non-union with open reduction internal fixation utilizing a tension band plate and screws. This interesting case highlights an uncommon cause of the relatively common presentation of posterior hip pain and describes our technique for addressing a stress fracture non-union in the ischium.

Pubic/ischial stress fractures after eccentric rotational acetabular osteotomy

BACKGROUND

Although there have been several reports on the complications of periacetabular osteotomy, stress fractures occurring in the pubic and ischial bones are less well recognised. The purpose of this study was to analyse the incidence of stress fracture, factors and treatment outcomes of stress fractures in the pubic/ischial bone after eccentric rotational acetabular osteotomy (ERAO).

MATERIALS AND METHODS

We examined 340 hips of 290 patients (male 35 hips, female 305 hips; mean age 42 years) with whom it was possible to conduct a minimum of 1 year of follow-up observations after ERAO. The following items were investigated: presence of a pubic/ischial stress fracture after surgery; gender; age; bilateral or unilateral osteoarthritis; height, weight and body mass index; preoperative and final stages of osteoarthritis of the hip; preoperative and final center-edge (CE) angle, acetabular head index and minimum joint space; preoperative and final Japan Orthopaedic Association score; and presence of a pubic discontinuity. We then compared cases with pubic/ischial stress fracture (fractured group) with those with no fracture (nonfractured group). For the fractured group, we also investigated the onset time of the fracture.

RESULTS

The fractured group consisted entirely of women with a mean age of 47 years, and comprised 10 (2.9%) of the 340 patient hips examined. A statistically significant difference was observed between the two groups in pubic discontinuities (fractured group 8/10, nonfractured group 16/330; P < 0.0001) and postoperative CE angle (fractured group; 43°, nonfractured group; 36°, P = 0.0338) according to univariate analysis. However, only the pubic discontinuity rate differed significantly between the groups according to multivariate analysis (P < 0.0001). In all cases, a pubic/ischial stress fracture occurred within 3 months after surgery, and all cases had bony union. Recurrent fracture occurred in only one hip. There was no difference in the clinical outcomes of the fractured and nonfractured groups at the time of final follow-up.

CONCLUSIONS

The patients with pubic discontinuities were significantly more susceptible to a pubic/ischial stress fracture after ERAO. The presence of a pubic/ischial stress fracture did not influence the clinical outcome.

Extraarticular fractures after periacetabular osteotomy

Extraarticular fractures of the pelvic ring after periacetabular osteotomy could impair stability of the acetabular fragment and cause poor clinical and radiographic outcomes. We evaluated 17 patients (17 hips) with fractures of either the ipsilateral os pubis (n = 12) or os ischium (n = 5) during the postoperative period after periacetabular osteotomy. Ischial fractures seemed more debilitating with two of five resulting in painful nonunions for which additional surgery was performed. In contrast, only one patient with pubic fracture had additional surgery. Ischial fractures took almost twice as long to achieve resolution of symptoms compared with pubic fractures, and when left untreated, asymptomatic nonunions developed in three of five. However, we observed no effect on acetabular fragment positioning or long-term clinical outcome. It is essential to be aware of this potential complication and realize it could be accompanied by substantial morbidity for patients during the rehabilitation period after periacetabular osteotomy, but does not seem to influence the longer-term outcome.

LEVEL OF EVIDENCE

Level IV, therapeutic study.