Periprosthetic stress fracture around a well-fixed type 2B short uncemented stem

Abstract

Despite the theoretical advantages of uncemented short stems, postoperative thigh pain is still matter of concern and can be attributed to different causes. We report a peculiar case of a stress fracture around a short cementless stem with cervico-metaphyseal fixation in an otherwise healthy patient. We implanted a MiniHip^TM stem in a 43 year-old male professional golf player for the treatment of primary osteoarthritis using a ceramic on ceramic bearing. Against medical advice, the patient started to play soccer at the 4th postoperative month and was completely asymptomatic to that extent; but at 8 months follow-up and without a history of trauma he started complaining about progressive hip pain. After ruling out infection and loosening, histological analysis from a bone biopsy confirmed the diagnosis of stress fracture. Although revision surgery was initially scheduled, pain started to decrease gradually with protected weight-bearing (crutches) and disappeared around the first postoperative year, remaining the patient asymptomatic at 2 and half years of follow-up, with radiographs depicting a healed fracture with a hypertrophic callus. We encourage surgeons to be aware of the existence of periprosthetic stress fractures as a source of thigh pain (sometimes intractable), and despite being infrequent, they should always be contemplated, providing that these cases can be managed conservatively with rest and limited weight-bearing. After this uncommon case, we suggest to align the stem in order to equally distribute loads onto the medial calcar and the lateral femoral cortical.

Figure 1

A Preoperative anteroposterior radiographs of a 43-yeard old male´s left hip with diagnosis of primary osteoarthritis B and C. Immediate postoperative anteroposterior (A) and lateral (B) radiographs showing adecuate implant positioning after implanting a MiniHip™ stem.

Figure 2

A and B. Anteroposterior (A) and lateral (B) x-ray views of the same patient's hip at 8 months of follow-up depicting bone remodelling and periosteal reaction located at the lateral and anterior femoral cortices (*), which correlated with unremitting pain that exacerbated with axial loading. No signs of prosthesis subsidence or loosening can be appreciated.

Figure 3

A and B. Fat-Sat magnetic resonance imaging sequences demonstrating intraosseous and periprosthetic bone oedema as well as soft-tissue inflammation at the coronal (A) and axial (B) views. C. Triple-phase bone scintigraphy showing high metaphyseal uptake surrounding femoral stem, especially at the lateral femoral cortical (*).

Figure 4

A and B. Coronal and sagittal computed tomography slices obtained at the time of bone biopsy, taken from the lateral femoral cortical at 9 months of follow-up depicting no evidence of stem loosening or sinking. C and D. 10x and 40x haematoxylin and eosin staining histological sections taken from a bone biopsy taken at the lateral femoral cortical of the patient's left hip at 9 months of follow-up. Pathology analysis reveals disorganized trabecular bone and cartilaginous tissue with peri-haversian bone formation areas and abundant capillaries (angiogenesis), as well as increased subperiosteal osteoblastic activity.

Figure 5

A and B. Left hip's anteroposterior and lateral radiographs at 2 and half years of follow-up, evidencing a hypertrophic callus (*) with no signs of stem loosening, being the patient completely asymptomatic.