Patients with longstanding hip fusion are predisposed to symptomatic degenerative changes of the lumbar spine, ipsilateral knee and contralateral hip. In such patients, conversion of hip arthrodesis to hip replacement can provide relief of such symptoms. However, this is a technically demanding procedure associated with higher complication and failure rates than routine total hip replacement. The aim of this study was to determine the early functional results and complications in patients undergoing hip fusion conversion to total hip replacement, performed or supervised by a single surgeon, using a standardised approach and uncemented implants. We hypothesised that a satisfactory functional improvement can be achieved in following conversion of hip fusion to hip replacement. Eighteen hip fusions were converted to total hip replacements. A constrained acetabular liner was used in 3 hips. Mean follow up was 5 years (2 to 15 years). Two (11%) hips failed, requiring revision surgery and two patients (11%) had injury to the peroneal nerve. Heterotopic ossification developed in 7 (39%) hips, in one case resulting in joint ankylosis. No hips dislocated. Conversion of hip fusion to hip replacement carries an increased risk of heterotopic ossification and neurological injury. We advise prophylaxis against heterotopic ossification. When there is concern about hip stability we suggest that the use of a constrained acetabular liner is considered. Despite the potential for complications, this procedure had a high success rate and was effective in restoring hip function

Hip fusion is an uncommon procedure. Hip fusion takedown, therefore, is equally an uncommon procedure. What is of considerable interest is that the results, which I achieved in 20 cases in a paper published in 1987 are considerably superior to the results, which I am achieving today. This suggests that no simple case is now fused. It also equally suggests that there is little sense in looking at literature more than 10 or 15 years old on fusion takedowns as the two conditions are likely completely different. Most patients do not like a hip fusion. There are long-term problems with low back pain, ipsilateral global instability and contralateral patellofemoral osteoarthritis. A stiff hip produces a poor quality of life, especially in a tall person. The main problem in doing a hip fusion takedown is the condition of the abductors muscles. If fused before growth was complete, there may be pelvic hypoplasia. If the pelvis is small, the glutei will also be small. Sometimes, the glutei may have undergone fatty degeneration. This can be assessed by means of an MRI. If the abductors were damaged during fusion, a limp may persist. Other problems are that leg lengthening is difficult to achieve any longstanding hip fusion. Lengthening of 1–2 cm is usually about all that can safely be achieved. If the hip was fused in childhood, there is likely to be femoral hypoplasia. There is also likely absence of proximal cancellous bone and the proximal femur is a thin brittle cortical tube. The greater trochanter should not be detached as it is difficult to obtain union under such circumstances. The approach, which I prefer for a fusion takedown is an anterior Smith Peterson. The glutei are slid off the pelvis sidewall and then the upper part of the fusion can be exposed, blunt Hohmans can then be passed around the femoral neck prior to transection. Obviously, if any AO cobra plate has been used for a fusion, a trochanteric osteotomy may be required to preserve any glutei left. Old hardware can be removed either concurrently or as an interval procedure. In 1986, I published the results of 20 cases with a five to 40-year fusion time (mean 19). I used a variety of implants. Flexion was achieved to 90 degrees at 12 months in about 88% of people. Seventy-five percent ceased to limp by year one, although the elderly limp when tired. One patient was dissatisfied with the procedure. One was revised for pain. I have reviewed the cases done in the last 20 years. These were 28 cases, two bilateral. Seven were spontaneous fusions. Twenty-one were formal hip fusions. One was an AO fusion with a cobra plate. There were various intra-operative complications including two calcar cracks, which were wired, three femoral shaft fractures, which necessitated the use of long stems. There was one drop foot, which recovered. At review, a limp was absent in 20%, mild in 12% and severe, i.e. Trendelenburg positive in 68%. Harris hip scores were excellent in 28%, good in 32%, fair in 16% and poor in 24%. Four patients only, however, continued to use canes. The eventual range of movement was good. In 80%, more than 90 degrees of flexion was obtained, but it took up to two years to obtain maximum flexion. In 12%, the range of motion was poor at being 50 degrees to 85 degrees. The range of motion was poor, i.e. less than 45 degrees in one bilateral case of athrogryposis. This was a stiff arthrogrypotic. Further surgery is required in several cases. An ipsilateral total knee replacement and one a supracondylar femoral osteotomy. One cup loosened and was revised at seven years and one liner was exchanged at ten years

Hip fusion used to be a common procedure in children and young adults, but it is now exceedingly rare. My results of hip fusion takedown more than 20 years ago were quite acceptable. Of 20 cases, 88% achieved more than 90 degrees of flexion and 75% stopped limping by the end of one year. The elderly would revert to limping when tired. As no simple hips are currently fused, the results of hip fusion takedown in the last 20 years are very much inferior. Of 28 cases, limp is absent in 20%, mild in 12% and severe in 68%. Range of motion is acceptable with 80% eventually achieving more than 90 degrees of flexion. There are complications, but these are quite manageable. The aseptic loosening rate is small and the longevity is high. Current implants, therefore, can easily handle the hip fusion takedown. As the incidence of limp is prohibitively high, additional techniques to reinforce the hip abductors either concurrently or more likely as a secondary procedure as suggested by Whiteside should be learned by all those proposing to carry out hip fusion takedown

The main challenges in hip arthrodesis takedown include the decision to perform fusion takedown and the technical difficulties of doing so. In addition to the functional disadvantages of hip fusion, the long-term effects of hip arthrodesis include low back pain and in some cases ipsilateral knee pain. Indications for fusion conversion to THA include arthrodesis malposition, pseudoarthrosis, and ipsilateral knee, low back, contralateral hip problems, and functional disadvantages of ipsilateral hip fusion. When deciding whether or not to take down fusion, consider the severity of the current problem, risks of takedown and likely benefits of takedown. Best results of fusion takedown occur if abductor function is likely to be present. If the abductors are not likely to function well, dearthrodesis may still help, but the patient will have a profound Trendelenburg or Duchenne gait and risk of hip instability will be higher. Abductor assessment can be performed by determining if the abductors contract on physical exam and determining if the previous form of fusion spared the abductors and greater trochanter. EMG and MRI also can be performed to assess the abductors, but value in this setting is unproven. Before dearthrodesis establish realistic expectations: most patients will gain hip motion—but not normal motion, most will see improvement in back/knee pain, but many will become cane-dependent for life. The main technical issues to overcome involve exposure, femoral neck osteotomy, acetabular preparation, and femoral fixation. Exposure can be conventional posterior, anterolateral or direct anterior with an in-situ femoral neck cut. In complex cases, a transtrochanteric approach is often helpful. The in-situ neck cut is facilitated by fluoroscopy or intraoperative radiograph to make sure the cut is at the correct level and at the correct angle. Be careful not to angle into the pelvis with the cut. Acetabular preparation is more complex because anatomic landmarks often are absent or distorted. Try to find landmarks including ischium, ilium, teardrop, and fovea. Confirm location with fluoroscopy as reaming commences and during reaming. Depth of reaming can be improved by using the fovea (if present) and teardrop on fluoroscopy. Cup fixation is usually an uncemented cup, fixed with multiple screws because bone quality typically is compromised. Femoral fixation is at the surgeon's discretion, recognizing the proximal bone may be distorted in some cases. Postoperative management includes protected weight bearing as needed and heterotopic bone prophylaxis in selected patients

The main challenges in hip arthrodesis takedown include the decision to perform fusion takedown and the technical difficulties of doing so. In addition to the functional disadvantages of hip fusion, the long-term effects of hip arthrodesis include low back pain and in some cases ipsilateral knee pain. Indications for fusion conversion to THA include arthrodesis malposition, pseudoarthrosis, and ipsilateral knee, low back, contralateral hip problems, and functional disadvantages of ipsilateral hip fusion. When deciding whether or not to take down a fusion, consider the severity of the current problem, risks of takedown and likely benefits of takedown. Best results of fusion takedown occur if abductor function is likely to be present. If the abductors are not likely to function well, dearthrodesis may still help, but the patient will have a profound Trendelenburg or Duchenne gait and risk of hip instability will be higher. Abductor assessment can be performed by determining if the abductors contract on physical exam and determining if the previous form of fusion spared the abductors and greater trochanter. EMG and MRI also can be performed to assess the abductors, but value in this setting is unproven. Before dearthrodesis establish realistic expectations: most patients will gain hip motion—but not normal motion, most will see improvement in back/knee pain, but many will become cane-dependent for life. The main technical issues to overcome involve exposure, femoral neck osteotomy, acetabular preparation, and femoral fixation. Exposure can be conventional posterior, anterolateral or direct anterior with an in situ femoral neck cut. In complex cases, a transtrochanteric approach is often helpful. The in situ neck cut is facilitated by fluoroscopy or intra-operative radiograph to make sure the cut is at the correct level and at the correct angle. Be careful not to angle into the pelvis with the cut. Acetabular preparation is more complex because anatomic landmarks often are absent or distorted. Try to find landmarks including ischium, ilium, teardrop, and fovea. Confirm location with fluoroscopy as reaming commences and during reaming. Depth of reaming can be improved by using the fovea (if present) and teardrop on fluoroscopy. Cup fixation is usually an uncemented cup, fixed with multiple screws because bone quality typically is compromised. Femoral fixation is at the surgeon's discretion, recognizing the proximal bone may be distorted in some cases. Post-operative management includes protected weight bearing as needed and heterotopic bone prophylaxis in selected patients

Purpose. The purpose of this study was to determine the functional outcome, imaging and complications of conversion of hip fusion to uncemented total hip replacement. Method. The study group comprised eighteen patients who had undergone conversion of unilateral hip fusion to total hip replacement between 1996 and 2007. There were five men and 13 women. The diagnosis prior to fusion was traumatic injury in eight patients, developmental dysplasia in three patients, and septic arthritis in seven patients. Four of the patient who had septic arthritis in childhood had spontaneous hips fusion while the other underwent surgical arthrodesis. The mean age at the time of conversion was 53 years (range, 21–77) and the mean time between fusion and conversion to hip replacement was 33 years (range, 11–60). Mean follow up was five years (range 2–15 years). Data was collected by retrospective review of a prospective database. Uncemented acetabular components were used in all cases and uncemented femoral components were used in all but two patients. In three patients with abductor and soft tissue deficiency an intraoperative decision was made to use a constrained acetabular liner. Results. The Harris hip score increased from a mean of 49 pre operatively to 75 at a mean of five years p<0.001. There was poor correlation between patient age, duration of hip fusion and hip scores at six months, 12 months and at final follow-up at a mean of five years. Heterotopic ossification developed in seven of the 18 (39%) patients. It was grade one in four patients, grade two in one patient, grade three in one patient and grade four in one patient. Four complications occurred in four of the 18 (22%) patients. Two patients (11%) had neurological injury in the common peroneal nerve distribution. In one patient heterotopic ossification resulted in joint ankylosis. This patient underwent reoperation to excise the heterotopic ossification 16 months after the initial hip replacement procedure. One patient developed a deep venous thrombosis. There were no hip dislocations. One acetabular component was loose and had migrated at 15 years follow up. Conclusion. Conversion of hip fusion to hip replacement carries an increased risk of heterotopic ossification and neurological injury. We advise prophylaxis against heterotopic ossification. When there is concern about hip stability we suggest that the use of a constrained acetabular liner is considered. Despite the potential for complications, this procedure had a high success rate and was effective in restoring hip function

Introduction. Management of the sequelae of arthritis of the hip joint has changed over time. Total joint replacement has gained popularity due to retained mobility and stability. In the high demand paediatric and adolescent population problems are encountered with longevity of the procedure. Hip arthrodesis is a useful alternative procedure that sacrifices mobility of the joint to achieve pain relief and restores function. Several surgical techniques have been described to achieve hip fusion. We describe a technique that achieves concentric bone surfaces with hip resurfacing reamers. Maximum bone is preserved to maintain leg length. Trans-articular compression is achieved with cannulated screw fixation. Subtrochanteric de-functioning osteotomy completes the procedure to protect the fusion site and control the position of the limb. Our optimal position of fusion was 30 degrees of flexion, neutral to 5 degrees of abduction and neutral to 10 degrees of external rotation. Methods. Fourteen patients (8 female) treated by hip arthrodesis over a two-year period are reviewed in terms of clinical and radiological outcome in the short term. Their mean age at hip fusion was 11 years (6–18). The etiology included TB (6 cases), staphylococcal infection (2), non-specific arthritis (3), Perthe's (1), chondrolysis (1) and avascular necrosis following trauma (1). Results. Fusion was achieved in 12/14 patients. All patients in whom fusion was achieved had relief of pain and returned to their normal activities. Conclusion. We believe hip arthrodesis performed in the correct patient is a good procedure to preserve function and relieve pain. The procedure is technically demanding and careful follow-up to ensure optimal positioning and solid fusion is essential to ensure good results. NO DISCLOSURES

Indications for removal of well-fixed cementless femoral components include infection, improper femoral height/offset/anteversion, and fracture. More recently, removal of well-fixed but recalled femoral components that are associated with adverse local tissue reaction (ALTR) has created a new indication for this procedure. The goal in all cases is to preserve bone stock and soft-tissue attachments to the greatest extent possible during implant removal. The strategy for implant removal depends to a large extent on the type of implant to be removed. Implants with limited proximal fixation can often be removed from the top using narrow osteotomes. Implants with more extensive fixation typically require more extensive exposure. When performing an extended trochanteric osteotomy, plan for the bone flap length based on measurement from the tip of the greater trochanter. Instead of devascularising the lateral bone flap, be sure to preserve the quadriceps attachment to the bone flap, exposing the lateral femur only where the transverse and posterior osteotomies are planned. The anterior osteotomy can be performed using a dotted line of osteotomes trans-muscularly as described by Heinz Wagner. Placement of a prophylactic cerclage below the osteotomy is prudent. Most importantly, if the need for a transfemoral exposure is likely, it should be performed primarily so that the posterior capsule and short rotators can be preserved. There is no need to perform a full posterior exposure and then to secondarily perform a transfemoral exposure since the former is unnecessary if the latter is performed. Discrete, limited fixation of the lateral bone flap proximally and distally should be performed to prevent strangulation of the living bone flap during the refixation process. The transfemoral technique can be applied not only to removal of well-fixed devices but also for conversion from hip fusion and for Z-shortening of the femur during Crowe 4 reconstruction instead of using a transverse osteotomy and intercalary shortening