After obtaining approval from our institutional review board (IRB number Pro00001774), we reviewed our centralized free vascularized fibular graft database. Twelve hundred and seventy vascularized fibular grafts were harvested for treatment of femoral head osteonecrosis in 946 consecutive patients between January 1990 and January 2006. All procedures were performed by one of two surgeons (J.M.A. III and J.R.U.), both of whom perform the procedure in an identical fashion. Six hundred and twenty-nine patients were male, and 317 were female. The average patient age was thirty-two years (range, nine to fifty-seven years). The duration of follow-up averaged 100 months (range, twelve to 212 months). At the time of the study, a minimum of five years had elapsed since 947 index procedures performed in 713 patients. Follow-up information was available for 86.6% (820) of these 947 procedures. In this series, chronic exposure to high-dose corticosteroids was the most frequent reason for the development of osteonecrosis of the femoral head (Fig. 1). According to the classification of Marcus et al., fourteen hips had a stage-I lesion; 331 hips, a stage-II lesion; 150, a stage-III lesion; 707, a stage-IV lesion; and sixty-eight, a stage-V lesion32. Patients with a stage-IV or V lesion are offered surgery only if hip motion is preserved and symptoms are minimal. A right fibular graft was obtained in 647 procedures and a left fibular graft, in 623 procedures. Of these patients, 324 underwent harvest of both fibulae in a staged fashion to treat bilateral hip disease.
Preoperatively, all patients were asked about any previous injuries or preexisting disorders of the lower extremities. The patients were examined postoperatively at three, six, twelve, and eighteen months; at two years; and then yearly thereafter by one of the two surgeons. In some cases, it was necessary for the follow-up evaluation to be completed by a local orthopaedic surgeon because the patient would have had to travel a considerable distance to our institution. Under these circumstances, our standardized evaluation form was provided to the orthopaedic surgeon who was conducting the follow-up examination. This form and radiographs were then forwarded for our review.
At each postoperative visit, patients were asked specifically about pain, sensory loss or abnormalities, motor weakness, and ankle instability. Any affirmative answer was recorded on their encounter data sheet as a positive finding. Sensory and strength testing of the operatively treated extremity was performed, and any objective deficits were recorded. Specific attention was paid to extensor hallucis longus and peroneal muscle function. The range of motion was compared with that on the contralateral side. Orthogonal radiographs were made of any patient who reported pain at the donor site. All data from the encounter sheets were transcribed into a centralized database.
Operative Technique
A technique that has been previously described in detail was used for all procedures3,33. It is no longer our practice to harvest bone graft from the lesser trochanter, as we believe that doing so may contribute to subtrochanteric fracture. Therefore, we harvest cancellous bone only from the greater trochanter. Over the years, there have been logistical modifications to make the procedure more expedient and accurate. These include simultaneously preparing the hip during the fibular harvest, the use of venous couplers, and recently the use of image guidance for guide pin placement.
Postoperative Regimen
A soft dressing, consisting of dressing sponges, cotton cast padding, and bias-cut stockinette, is applied to the fibular harvest site. Patients receive aspirin, dextran, and dipyridamole postoperatively, and an epidural catheter is used for continuous pain control. The limb is placed in an air boot (Foot WAFFLE; EHOB, Indianapolis, Indiana) to prevent excessive heel pressure while the epidural block is in place. Physical therapy begins on the first postoperative day with an emphasis on stretching exercises for the great toe to prevent a flexion contracture. The patient is mobilized out of bed on the second postoperative day and typically is discharged home on the third postoperative day, with follow-up scheduled at six weeks. During this six-week period, the patient remains non-weight-bearing on crutches and is encouraged to perform strengthening and range-of-motion exercises of the hip, knee, and ankle. This regimen is designed to limit loss of motion and strength while preventing a fracture of the femoral neck, which is transiently weakened by the large-caliber tunnel drilled to accommodate the fibular graft. The patient is instructed to continue taking aspirin and dipyridamole until the six-week follow-up visit.
Source of Funding
No external funding was received for this study.
Overall, 215 complications (a 16.9% rate) occurred after the 1270 procedures involving use of an autogenous vascularized fibular graft for treatment of osteonecrosis of the femoral head. Of the 215 complications, 67.9% (146) consisted of donor site morbidity (Table I) and 32.1% (sixty-nine) consisted of graft site morbidity (Table II). Overall, the prevalence of donor site complications was 11.5% (146 of 1270) and the prevalence of graft site complications was 5.4% (sixty-nine of 1270). The rate of pain, tenderness, and instability (3.6%) was nearly equivalent to that in our previous report (4.1%)3. As compared with our previously reported findings, the present study demonstrated lower rates of persistent motor weakness (10.1% compared with 0.6%), sensory symptoms (4.9% compared with 0.7%), and proximal femoral fracture (2.5% compared with 0.6%).
A major complication, defined as one requiring a reoperation or chronic medical management, was observed after fifty-four (4.3%) of the 1270 procedures. The treatment of these complications included hardware removal in nineteen patients, tendon lengthening in twelve, femoral fracture fixation in nine, treatment of deep infection in four, removal of heterotopic bone in three, neurolysis in two, sensory nerve repair in one, and hematoma evacuation in one. In addition, three patients with a history of fibromyalgia required chronic pain management because of the new onset of postoperative pain.
Donor Site Morbidity
Great-Toe Contracture
The most frequent complication after fibular graft harvest was a flexion contracture of the great toe. There was some degree of great-toe flexion contracture in the first year following fifty-four (4.3%) of the 1270 procedures. Most of these patients were asymptomatic as the contracture was noticeable only on physical examination with the ankle fully dorsiflexed. Twelve patients, however, required z-lengthening of the flexor hallucis longus tendon at the level of the medial malleolus to treat postoperative scarring and contracture. Four of these patients also had a lesser degree of flexion contracture of the second and third toes. This was indirectly addressed by the z-lengthening of the flexor hallucis longus through its intertendinous connections with the flexor digitorum communis. Lengthening of the flexor hallucis longus successfully corrected the contracture in all twelve patients, and no additional complications occurred.
Motor Weakness
At the early follow-up visits, most patients had transient motor weakness in the operatively treated extremity. This appeared to be largely attributable to pain inhibition. However, by the twelfth postoperative week, eight (0.6%) of the 1270 procedures demonstrated persistent weakness on clinical examination. There were no complete nerve palsies, and all eight patients exhibited moderate, but not full, strength. The long-toe flexors were affected in six of the eight patients, whereas the other two exhibited extensor or peroneal weakness. One patient underwent operative neurolysis of the peroneal nerve. This decreased the symptoms, but motor recovery was incomplete. The others had improvement over time and required no additional treatment.
Pain
Any history of, or present, pain or tenderness was recorded at each postoperative visit. Ankle pain or tenderness occurred following fifty-two (4.1%) of the 1270 procedures and accounted for 35.6% of the 146 donor site complications. Corroborating the findings of our previous series3, the ankle and distal osteotomy site remained the most common location for pain and tenderness. The patients noticed pain mostly after prolonged standing or moderate activity such as jogging. The discomfort was usually mild, and all but three patients were managed satisfactorily with nonsteroidal anti-inflammatory medications. Three patients, with a history of fibromyalgia and narcotic dependence, required prolonged multimodal pain management for surgical site discomfort. No patient underwent surgical management for this symptom.
Sensory Deficits
Any subjective or objective sensory loss was recorded as an abnormal finding. Twenty-one (1.7%) of the 1270 procedures demonstrated sensory loss in the operatively treated extremity. This constituted 14.4% of the 146 donor site complications in our series. The loss was isolated to specific regions of the ankle or foot, although it was not always consistent with peripheral nerve or dermatomal distributions. The superficial peroneal nerve was most frequently affected. It was completely transected in one patient, and it was repaired at the index procedure, resulting in partial recovery. In one additional patient, neuropathic symptoms completely resolved after exploration and neurolysis of an intact common peroneal nerve. Sensory changes in thirteen patients became clinically irrelevant or resolved over time. Plantar sensation and the ambulatory status were not affected in this series. Anecdotally, a postoperative donor site hematoma requiring evacuation developed in one patient treated outside the time frame of this study. This resulted in complete neurapraxia of the plantar aspect of the foot. Heel pad sensibility had returned five months postoperatively; however, at that time, the patient remained insensate distal to the middle of the arch.
Graft Site Morbidity
Kirschner Wire Migration
A Kirschner wire was used routinely to secure the fibular graft in its final position after the graft had been placed in the femoral head. The most frequent graft (hip) site complication was symptomatic lateral migration of the Kirschner wire in thirty (2.4%) of the 1270 procedures. Kirschner wire migration was frequently asymptomatic and was followed radiographically. The patients who were symptomatic described local tenderness. Eleven had improvement after a local corticosteroid injection and physical therapy, and the other nineteen patients required pin removal. No residual symptoms were experienced after pin removal.
Heterotopic Ossification
Heterotopic ossification was often apparent on routine follow-up radiographs of asymptomatic patients. Symptomatic heterotopic ossification was experienced by eighteen (1.4%) of the 1270 procedures. These patients described pain and tenderness over the lateral aspect of the proximal part of the femur, mostly when they were attempting to sleep on the operatively treated side. Three patients underwent surgical excision with radiation therapy to prevent recurrence, and all three had relief of the symptoms postoperatively.
Deep Venous Thrombosis
Four deep venous thromboses (a rate of 0.3%) were diagnosed in our series postoperatively. While a pulmonary embolism was suspected in two patients, imaging studies were negative and no pulmonary emboli were diagnosed.
Femoral Fracture
Nine fractures (a rate of 0.7%) were documented following the vascularized fibular transfers. These fractures all occurred in the intertrochanteric and subtrochanteric region after a fall, and they were treated acutely with open reduction and internal fixation. On the basis of the specific fracture characteristics, six condylar screws, two dynamic hip screws, and one blade-plate were utilized. A nonunion developed in two of the nine patients and required iliac crest bone-grafting, which led to healing in both cases. Eight of the nine patients continued to have good results and required no additional surgery at an average of seven years following fracture fixation. One patient underwent conversion to a total hip arthroplasty fourteen years postoperatively to treat progressive hip arthritis and pain.
Infection and Hematoma
Thirteen superficial infections and four deep infections developed. Superficial infections were defined as those not requiring operative irrigation and débridement. Ten of these occurred at the donor site, and three were present at the graft site. All were treated with antibiotics and had no long-term sequelae. Four deep infections occurred, three at the graft site and one at the donor site. They required formal irrigation and débridement, closure over drains, and intravenous antibiotics with the coverage and duration determined by infectious disease specialists. None of the grafts in these patients were removed.
One large hematoma underwent operative evacuation on the second postoperative day. Pain and tenderness developed along the hip incision, and a mass deep to the incision was evident clinically. At surgery, no actively bleeding vessels were identified and the anastomosis was found to be intact and functioning. The wound was closed over bulb suction, and the patient recovered uneventfully.
An autogenous vascularized fibular graft is used frequently and for many major reconstructive purposes because it provides structural stability and it has a reliable vascular supply. Its versatility and advantages over other graft types have been well documented in the literature4,5,8-12,14-16,34-36. The reported morbidity of this procedure has been variable2,3,6,19-23,26,28,37-39.
At first glance, the overall complication rate of 16.9% in this series seems high. Although inconvenient, more than two-thirds of these complications were minor, asymptomatic, or transient. There were relatively few major complications (a 4.3% rate [fifty-four of 1270 procedures]) requiring additional procedures or chronic pain management. The rates of persistent motor weakness, sensory symptoms, and proximal femoral fractures have decreased since we described our earlier experience3. We attribute these decreases to increased experience, an awareness of these specific complications, and meticulous handling of the neurovascular structures. Furthermore, we no longer harvest cancellous bone graft from the lesser trochanter. This, in addition to strictly enforced weight-bearing prohibition during the first six postoperative weeks, appears to have successfully decreased the fracture rate from 2.5% to 0.7%40.
Flexion contracture of the great toe was the most frequent donor site complication in this series, and the rate was higher than what we previously reported3. We became more aware of this frequently subtle complication after our previous report, and we identified a number of clinically asymptomatic contractures, many of which became apparent only after comparison with the contralateral extremity. We believe that the loss of muscle origins due to fibular removal causes the contracture and a tenodesis effect of the long-toe flexor tendons. Our physical therapists now routinely begin toe-stretching exercises on the first postoperative day, and patients are asked to continue the exercises daily for a minimum of six weeks postoperatively. Patients who were found to have decreased motion in the early postoperative period were asked to resume toe-stretching exercises. Despite this protocol, twelve flexor hallucis longus z-lengthening procedures were performed in symptomatic patients because of a failure of the contracture to improve or because of substantial disability. The procedures were performed on an outpatient basis, and all patients recovered completely with no further symptoms.
Motor weakness may be the most troubling complication for patients postoperatively. The reported prevalence of these deficits has varied. Zimmermann et al.21 described reduced strength following 45% of forty-two fibular harvests performed for oncologic reconstruction. They noted that these deficits improved with time, in contrast to the reports of others3,19. No complete motor palsies occurred in our series, and most cases of motor weakness, although worrisome and inconvenient, did not limit the patient's capacity to walk. The rate of persistent motor weakness decreased from approximately 10% in our previous series3 to <1% in the present study. Our fibular harvest and data collection techniques did not change from those used in our previous study, in which the treatment period ended in 1990. We attribute the decreased rate of motor weakness to an increased awareness of the complication, meticulous retraction of the deep peroneal nerve, and our overall increased experience with the procedure.
Pain, tenderness, and instability of the ankle are also frequently described complications of fibular harvest3,27,41,42. None of our patients reported instability of the operatively treated extremity and, compared with other reports25,27, relatively few reported pain. The rate of these complications (3.6%) is largely unchanged from that in our previous report (4.1%)3. Some protocols allow weight-bearing on the first postoperative day with progression as tolerated21. Because our patients are under strict weight-bearing restrictions for a minimum of six weeks secondary to the concurrent hip procedure, it may not be practical to generalize our results to all populations. The delayed weight-bearing may provide time for the residual fibula to stabilize, decreasing the risk of instability and pain. Valgus deformity and instability of the ankle are infrequently reported in children30, and a syndesmotic screw should be placed in all patients with open physes. In this series, sixty-six patients under the age of fifteen years underwent syndesmotic fixation. While our experience with performing this procedure in children is more limited than our experience with adults, we are aware of no valgus ankle deformities developing in our pediatric patients. We are aware that one of our patients, not included in the present series, was discovered to have a leg-length discrepancy requiring surgical treatment. It is uncertain if this length discrepancy was a result of the surgical procedure or had been present preoperatively.
Sensory deficits have also been frequently reported in the literature describing complications of fibular harvest. We previously reported a sensory complication rate of 4.9%3, and paradoxically the rate had seemed to increase during the follow-up period. In contrast, several authors have suggested that sensory and motor deficits decrease with time21,43. Although we do not have access to data to allow us to differentiate between sensory deficits at early and distant postoperative time points, the total rate of sensory symptoms in the present series (1.7%) was lower than what we reported previously3 (4.9%). Again, because our surgical and data collection techniques did not change, we attribute this to increased awareness, experience, and intraoperative protection of the nerves.
Graft site complications are unique to fibular transport for the treatment of osteonecrosis of the femoral head. Considering that 32.1% of the complications in our series were at the hip, the morbidity at this site was not trivial. At surgery, a single Kirschner wire is placed to prevent initial migration of the fibular graft. Although it was commonly asymptomatic, radiographic evidence of wire migration was the most frequent complication encountered in this area. Most symptomatic patients described tenderness or discomfort along the lateral aspect of the femur. Migration was always lateral, and it caused no problems other than these symptoms. Migrated wire required removal on an outpatient basis in nineteen patients, and symptoms resolved in all cases.
Heterotopic ossification is often noticeable on routine postoperative radiographs in asymptomatic patients. It probably forms secondary to reaming and bone-grafting of the femoral head. In eighteen of our patients, it became symptomatic and was described primarily as tenderness while the patient tried to sleep on the affected side. All patients initially received an injection of local anesthetic and corticosteroids, which served both diagnostic and therapeutic purposes. Despite this conservative management, surgical removal was required in three patients. Because of the small number of symptomatic patients, we do not routinely provide prophylaxis against heterotopic ossification unless resection is necessary. The rates of heterotopic bone formation in this series were decreased compared with those in previous reports44.
Thromboembolic complications are a concern following any lower-extremity surgery. Four deep venous thromboses were diagnosed in our series (a rate of 0.3%), and no pulmonary emboli were detected. Because all of our patients underwent two ipsilateral surgical procedures (at the donor and graft sites), our reported thromboembolism rate may not be applicable to all populations undergoing fibular harvest. We attribute our low rate to two major factors. First, the patients routinely received aspirin, dipyridamole, and dextran, to preserve vessel patency, while they were in the hospital. Also, daily aspirin and twice-daily dipyridamole were prescribed for the first six postoperative weeks. The routine use of these medications may offer some protection against thrombosis. Second, there was no immobilization period. Our patients began, under the supervision of a therapist, active, non-weight-bearing, range-of-motion exercises on the first postoperative day, and the patients were instructed to continue these exercises for six weeks.
In this procedure, the femoral neck and subtrochanteric region are transiently weakened secondary to removal of a large-diameter bone core, reaming, and bone graft harvest. Nine femoral fractures occurred in our series, and all were sustained in an incident in which full weight was borne by, or direct impact occurred to, the proximal part of the femur. The patients were treated with acute internal fixation as dictated by the fracture type. Our fracture rate decreased from 2.5% to <1% after we changed the postoperative weight-bearing status from touch-down to non-weight-bearing40. Additionally, we no longer harvest cancellous bone graft from the lesser trochanter in an effort to not weaken this area further. Since 1990, the prevalence of subtrochanteric fractures has decreased to 0.7% after this modification of technique. Therefore, it remains our practice to harvest cancellous graft only from the greater trochanter.
Limitations of this study are related to the exclusive evaluation of patients who underwent fibular grafting for the treatment of osteonecrosis of the femoral head. The average age of such patients is nearly a decade younger than that of patients treated with a fibular graft for other reconstructive purposes21. The higher proportion of younger patients may bias our population toward an increased activity level or a better healing capacity and less musculoskeletal or medical comorbidity. In addition, patients are often allowed to bear weight as tolerated shortly after a fibular harvest alone6,21,23. In contrast, our population underwent a concurrent ipsilateral hip procedure that required six weeks of weight-bearing restriction. This may have directly influenced donor site morbidity by allowing healing to occur prior to the loading of disrupted structures. The additional ipsilateral procedure may also have influenced the patients' perception of morbidity at each surgical site.
We recognize the limitations of a retrospective review of prospectively collected data. Some data points were collected by other physicians when it was inconvenient for patients living a considerable distance from our institution to travel for routine follow-up appointments. In all cases, our standardized evaluation form was utilized and the radiographs were reviewed by us. The potential for inaccuracy is also limited because each patient was evaluated by us personally on a number of other occasions.
We also acknowledge that the loss of patients to follow-up may influence results. Although few additional complications were noted outside the initial postoperative period, it is possible that patients may have been treated for complications at other institutions. Although a detailed discussion is outside the scope of this review, reasons for discontinued follow-up include conversion to hip arthroplasty or fusion, death from unrelated causes, and simple loss to follow-up.
In conclusion, autogenous vascularized fibular transfer to treat osteonecrosis of the femoral head is associated with a measurable morbidity risk. Restricting postoperative weight-bearing, limiting cancellous bone harvest to the greater trochanter, and handling neurovascular structures meticulously can minimize the morbidity risk. Surgeons and patients should, however, continue to weigh the morbidity risk with the potential benefit of this surgical procedure.