Sugiokas transtrochanteric rotational osteotomy, as a treatment of osteonecrosis of the femoral head, has variable success rates. Its known complications include: progressive varus deformity, femoral neck fracture, and femoral head collapse. However, femoral head stress fracture has not been described as a complication of Sugiokas transtrochanteric rotational osteotomy. This article presents cases of 2 of 64 patients who underwent Sugiokas transtrochanteric rotational osteotomy between 1994 and 2006 and experienced femoral head stress fractures. Both patients were young and active. They presented with acute inability to bear weight and pain on the operated hip after mountain climbing 1 and a half to 3 years following the index surgery. Diagnosis of femoral head stress fracture was established by the presence of an inferolaterally-directed vertical fracture line from the superolateral aspect of the femoral head on computed tomography scans for both patients. One patient was successfully managed with conservative measures, whereas the other underwent total hip replacement after failed conservative treatment.
We hypothesize that the direction alteration of the trabecular system due to proximal femoral segment rotation, varus positioning of the proximal femur, and inadequate placement of the screw into the necrotic femoral head may have caused the femoral head stress fractures after transtrochanteric rotational osteotomies. Stress fracture of the femoral head is a potential complication following Sugiokas transtrochanteric rotational osteotomy for osteonecrosis of the femoral head, which may be prevented by avoiding heavy exercises such as mountain climbing, until adequate remodeling of the trabecular system is gained and screws can be inserted into the femoral head subchondral bone as deeply as possible with avoidance of the necrotic area.
Osteonecrosis of the femoral head, without proven methods to arrest the disease process, will progress with subchondral collapse, reduced joint space, and subsequent development of osteoarthritis of the hip joint. It has a poor prognosis. Although any age group may be affected, it is more common in the young and middle-age groups.1-5 Depending on the stage of the disease, various surgical treatments like core decompression, decompression and bone grafting (both structural and vascularized fibular grafting), muscle pedicle graft, osteotomies around the proximal femur, and head salvage procedures like hip resurfacing and total hip replacements (THRs) have been described.6
In 1978, Sugioka et al7 reported using transtrochanteric anterior rotational osteotomy to reposition the necrotic anterosuperior part of the femoral head to a nonweight-bearing locale by rotating the femoral head and neck anteriorly along the longitudinal axis and bringing the uninvolved posterior articular surface of the femoral head to a weight-bearing area, hence, withdrawing mechanical stresses from the necrotic lesion. The success rates range from 73% to 91% depending on the severity of osteonecrosis of the femoral head.8
The subchondral portion is a common fracture site in osteonecrotic femoral heads. However, another common fracture site is the junction of the necrotic and reparative bone and this junction is in the subcapital area when osteonecrosis involves the whole femoral head.9
Femoral neck fracture can develop after Sugiokas transtrochanteric rotational osteotomy with an incidence rate of 1% to 15%.6,8,10,11 However, no cases of femoral head stress fracture following Sugiokas transtrochanteric rotational osteotomy have been reported to the best of our knowledge. This article presents 2 such patients, both of whom were nonprofessional mountain climbers.
A 45-year-old man who was a weekly mountain climber presented with a history of bilateral hip pain. On examination, he had terminal restriction of hip movements and a preoperative Harris Hip Score12 of 75. Radiographs revealed bilateral femoral head osteonecrosis in stage 2 of Ficat-Arlet classification13 and Type C2 of Suganos classification14 on magnetic resonance imaging (MRI) (Figure 1A). Twenty days after the diagnosis of osteonecrosis, the patient underwent Sugiokas transtrochanteric rotational osteotomy stabilized with four 6.5-mm cannulated cancellous screws on the left side and 4 months later on the right side.
|Figure 1: MRI showing Sugano's type C2 osteonecrosis in both femoral heads (A). Radiograph taken 27 months following osteotomy on the right side showing union and remodelling of the osteotomy, stabilized with multiple cannulated cancellous screws with healing necrosis and a well-maintained femoral head contour without collapse and preserved joint space (B). |
Postoperative periods were uneventful and the patient was kept in skin traction for 2 weeks with intermittent quadriceps and active range of motion exercises. Nonweight-bearing crutch walking began 2 weeks postoperatively for 3 months, followed by partial weight bearing for another 3 months with crutches. Postoperative Harris Hip Score improved to 96. The patient was allowed full weight bearing after 6 months. Radiographs taken at 6 months postoperatively showed complete union at the osteotomy site. The patient was followed up every 6 weeks for the first 6 months and then every 2 months for another 6 months (Figure 1B).
After 2 years and 7 months, the patient presented with acute right hip pain and inability to bear weight on his right lower limb after continuous mountain climbing for 6 to 7 hours. No history of trauma was recalled. The physician took radiographs and the fracture was neglected.
The patient presented with continued pain. On physical examination, he had painful movements of the right hip. Radiograph and computed tomography (CT) scans taken 10 days after the development of hip pain showed a vertical undisplaced fracture of the right femoral head (Figure 2A).
|Figure 2: CT scan taken 10 days after onset of right hip pain showing a stress fracture of the femoral head (white arrows) well separated from the necrotic area (red arrows) with normal bone in-between (A). Radiograph taken after 16 months of fracture detection showing fracture union with minimal displacement and subchondral collapse and with Sugioka’s transtrochanteric rotational osteotomy on the left side (B). |
The patient remained in Bucks traction for 2 weeks and was discharged with nonweight-bearing crutch walking for 3 months. Partial weight bearing was advised for another 2 months and full weight bearing was begun after 5 months from the time of femoral head fracture diagnosis. The patient was followed-up every month and routine hip radiographs and CT scans were performed at 3 months to evaluate the fracture healing. The last follow-up radiograph, taken 16 months after femoral head fracture detection, showed complete fracture healing (Figure 2B).
A 41-year-old man, who mountain climbed 4 to 5 hours a week, was diagnosed with osteonecrosis of the femoral head with a Ficat-Arlet classification of stage 2 and Suganos classification type C2 (Figure 3A). On examination, the Harris Hip Score was 73 with terminal restriction of movement.
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|Figure 3: MRI showing Sugano's type C2 osteonecrosis of the right femoral head involving the anterolateral portion (A). AP radiograph of the right hip joint taken 12 months after the Sugioka operation showing the implant in situ, with complete union and remodeling of the osteotomy site, no collapse of femoral head, and maintained joint space (B). CT scan taken 7 days after the reports of hip pain showing a minimally displaced vertical fracture of the femoral head involving the anterolateral portion (C). CT scan showing further displacement after 4 months of conservative treatment (D). |
Core decompression was performed 2 weeks after diagnosis. However, the pain did not subside and Sugiokas transtrochanteric rotational osteotomy was performed on the same hip 7 months later with a 125° dynamic hip screw. Postoperative rehabilitation was similar to patient 1, and the patient was allowed routine activities and full weight bearing while walking 5 months postoperatively after confirming osteotomy healing on radiographs (Figure 3B).
Approximately 1.5 years after transtrochanteric rotational osteotomy, the patient presented with displaced vertical fracture of the anterolateral femoral head (Figures 3C, 3D) following a similar history of mountain climbing for approximately 4 consecutive hours a week. The patient underwent THR after 4 months of failed conservative treatment.
Transtrochanteric rotational osteotomy for osteonecrosis of the femoral head was reported by Sugioka in 1978,7 showing variable results overall but relatively good results in Asian countries. Common complications of transtrochanteric rotational osteotomy include: progressive varus deformity, femoral neck fracture, and leg-length discrepancy. Sugioka et al8 reported 4 femoral neck fractures, 1 lesser trochanter fracture, 5 delayed unions, 2 postoperative avascular necroses, 1 avascular necrosis in the new weight-bearing area, and 2 osteoarthritis cases as complications of 474 hips (378 patients), with idiopathic and steroid-induced osteonecrosis of the femoral head after transtrochanteric rotational osteotomy.
Sugano et al11 had excellent clinical and radiological success results in 56% of patients in their study of 41 hips (40 patients). They experienced complications such as 6 femoral neck fractures, 1 pseudarthrosis at the osteotomy site, 3 osteoarthritis diagnoses, and 9 head collapses within 3 years of the osteotomies. Biswal et al10 reported 3 femoral neck fractures, 10 progressive collapses, 7 progressive varus deformities, and 1 infection out of 64 hips that underwent Sugiokas transtrochanteric rotational osteotomies.
From April 1994 to February 2006, we performed 64 (53 patients) transtrochanteric rotational osteotomies for osteonecrosis of the femoral head. Sixty hips in 50 patients were available for follow-up and minimum follow-up was 18 months (range, 18-156 months). From this cohort, we identified several complications such as progressive femoral head collapse (10 patients), a mean of 8-mm leg-length discrepancy (range, 4-12 mm), and stress fracture (2 patients).
Because CT scans reveal subchondral fractures more clearly in osteonecrosis of the femoral head than unenhanced radiography or MRI, we used CT scans to find out the exact nature of the fracture and to judge the extent of the head collapse following transtrochanteric rotational osteotomy for follow-up.
In our 2 cases of stress fractures, fracture lines were detected at the superolateral area of the femur head, and directed to the inferolateral aspect of the femur neck. Fracture lines were just medial to the hip screw tip and the end of the cannulated screw. The necrotic portion of the femoral head was located inferomedially and far away from the fracture line (Figures 2A, 3C, 3D). The trigger for the fracture occurring at the mentioned location of the femoral head remains unknown. We assume 70° to 90° of the proximal femoral segment rotation, varus position of the proximal femur, and disproportionate mechanical stresses during weight-bearing and mountain climbing may be some of the causes of the femoral head fractures after transtrochanteric rotational osteotomy.
The internal trabecular system of the femoral head was first described by Ward in 1838.15 The orientation is along lines of stress, and thicker lines come from the calcar and rise superiorly into the weight-bearing dome of the femoral head. Forces acting in this arcade are largely compressive. Lesser trabecular patterns extend from the inferior region of the foveal area across the head and superior portion of the femoral neck into the trochanter. Forces acting in this arcade are tensile. According to Sugioka et al8 and Sugano et al,11 anterior rotation of the femoral neck may change the force-bearing trabecular architecture and place considerable strain on it, making it poorly adapted to the new load-bearing conditions, which may lead to fracture of the femoral neck. Unfortunately, adequate remodeling may take a long time. Sugano et al11 emphasized the need for a more solid method of fixation and mechanical reinforcement of the neck.
We used three or four 6.5-mm sized cannulated screws and 125° dynamic hip screws for fixation after osteotomy. Generally, cannulated screws and hip screws for the femoral neck fracture fixation are recommended to be inserted deeply in the subchondral bone of the femoral head. However, it is difficult to insert fixatives deeply because of the necrotic area of the femoral head. In our 2 patients, fixatives were located at the femur neck and distal area of the femur head to avoid violation of the necrotic area. It is also attributable that the cantilever bending movement (about the fractured area) may have created shear forces at the hip screw and cannulated screw tips and led to the fracture of the head. During mountain climbing, the hip frequently goes into flexion, abduction, and internal and external rotations. A single hip, alternatively, bears the whole body weight and has to bear 3 to 6 times more body weight than that of the normal gait stance phase.6
Stress fracture of the femoral head is a potential complication following Sugiokas transtrochanteric rotational osteotomy for osteonecrosis of the femoral head, which may be prevented by inserting screws into the subchondral bone as deeply as possible with avoidance of the necrotic area and a careful postoperative rehabilitation program. In individuals with a normal lifestyle, a regular postoperative rehabilitation program as described by Sugioka is optimal, but individuals who engage in heavy exercises like mountain climbing should avoid it for at least 2 to 3 years. However, further reports and studies are required to establish evidence.
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Mr Chotai and Dr Shon are from the Department of Orthopedics, Korea University Guro Hospital, Seoul, and Drs Suh and Han are from the Department of Orthopedics, Korea University Ansan Hospital, Ansan City, Korea.
Mr Chotai and Drs Shon, Suh, and Han have no relevant financial relationships to disclose.
Correspondence should be addressed to: Won Yong Shon, MD, PhD, Department of Orthopedics, Korea University Guro Hospital, Guro 2-dong, Guro-gu, Seoul, Korea, 152-703 (email@example.com).