Ipsilateral stress fracture of the proximal fibula after total knee arthroplasty in a patient with severe valgus knee deformity on a background of Rheumatoid arthritis

Calcaneal insufficiency fractures following ipsilateral total knee arthroplasty

INTRODUCTION

Only a few reports have described calcaneal insufficiency fractures (IFs) following total knee arthroplasty (TKA). Herein, we describe nine cases of calcaneal IFs following ipsilateral TKA. The purpose of this study was to investigate the incidence of calcaneal fractures following TKA and determine the characteristics of patients with IFs.

PATIENTS AND METHODS

We retrospectively investigated cases of calcaneal IF that occurred following TKA. We collected and analyzed radiographic and magnetic resonance imaging (MRI) findings as well as patient demographic data. We compared the demographic data, bone mineral density (BMD), and preoperative hip-knee-ankle angle (HKA) between cases with a calcaneal fracture following TKA and 100 cases without a fracture following TKA.

RESULTS

We performed a total of 1548 knee arthroplasties at our clinic from 2011 to 2020. Nine calcaneal IFs in eight patients were diagnosed following ipsilateral TKA. All patients were women with varus knee osteoarthritis (mean age, 71.8 years). The average change in the alignment angle was 14.7° ± 5.4°. In eight cases, dysfunction was observed in the opposite lower limb. The postoperative onset of hindfoot pain started at an average of 5.6 months. In seven patients, calcaneal fractures occurred idiopathically, but in one patient, two fractures occurred after long-distance walking. No abnormal findings on a calcaneus radiograph were seen for six fractures. MRI demonstrated a definite fracture line and bone marrow edema in all patients. All patients, except one with type 2 diabetes mellitus (T2DM), had osteoporosis. Fractures healed without complications in eight patients; however, the calcaneal anterior facet fracture became displaced and caused a flat foot in one case. The calcaneal IF rate was 0.58% among all cases. Besides one case with T2DM, significant differences were observed in preoperative HKA and BMD between cases with a calcaneal fracture following TKA and those without a fracture.

CONCLUSIONS

A change in the load on the calcaneus due to changes in the alignment of the lower extremities after TKA may cause calcaneal IFs. Orthopedic surgeons should be aware of the possible occurrence of calcaneal IFs following TKA, especially in women with osteoporosis and severe varus knee.

Acute presentation of a proximal fibular stress fracture after a total knee arthroplasty

A 67-year-old woman underwent a routine and uneventful elective total knee arthroplasty for osteoarthritis at our centre. No intraoperative nor immediate postoperative complications were noted clinically nor radiologically. At 5 weeks postoperative, she began to notice some new discomfort in her upper calf area, with no preceding history of trauma. A Doppler ultrasound scan ruled out a deep vein thrombus. Only on further re-imaging of her knee with X-rays and CT was there shown to be a fibular fracture of the proximal third with evidence of callus formation. The pain arising from her stress fracture delayed her rehabilitation slightly, going on to require a successful manipulation under anaesthetic (0°-95°). She went on to have excellent function in her knee and the pain from the stress fracture had settled by 5 months.