1 Introduction

Surgical dislocation of the hip was first described in 2001 by Ganz et al.¹ The approach was a result of an extensive anatomical research on the blood supply to the femoral head.² The medial circumflex femoral artery, which is the main blood supply, is protected by an intact obturator externus muscle. A trochanteric flip allows anterior exposure of the capsule, and a controlled anterior dislocation of the hip is carried out. This allows a gap of up to 11 cm between the head and the acetabulum, giving a view of the femoral head of about 360° and a full 360° view of the acetabulum.¹ A number of hip conditions have been treated with this approach like femoroacetabular impingement, various paediatric hip diseases and benign tumours around the hip like intraarticular exostosis, synovial chondromatosis and aneurysmal bone cysts.^1,3–6 In their original series, Ganz et al utilized this approach for PVNS, synovial chondromatosis and cartilage exostosis.¹ We present our experience of this approach in which multiple benign tumours were excised through surgical dislocation of the hip joint.

2 Patients and methods

This is a retrospective review of patients with symptomatic benign tumours of the hip that presented to our complex hip clinic in a tertiary care hospital. A detailed history was taken and clinical examination including hip range of motion and impingement test⁷ were carried out. Anteroposterior pelvic radiographs with lateral of the hip were carried out for all patients. Further investigations included magnetic resonance imaging (MRI) in all patients, whereas computed tomography (CT) scans with 3D reconstruction were carried out in selected cases to study detailed anatomy, pattern of joint and bone involvement. Following clinical and radiographic diagnosis all cases were discussed with multidisciplinary team for appropriate management plan.

Patients were consented for surgical dislocation of the hip and excision of the tumours. The procedures were performed by the senior author (SP) along with tumour surgeon (AM). Ganz trochanteric slide approach with anterior surgical dislocation was carried out in all patients as described in the literature.¹ Blood supply to the femoral head was identified in all cases and protected throughout the procedure. Complete excision of tumours was carried in all cases. Additional procedures were carried out in 3 cases; 2 osteochondroplasties and 1 labral debridement. Samples were sent for histology in all cases for confirmation of diagnosis. Three patients required prophylactic insertion of compression hip screw due to extensive cavity formation in the femoral neck following tumour excision. Patients were mobilized partial weight-bearing for 6 weeks. All patients were followed-up in clinic at 6 and 12 weeks and 6 monthly. All patients had non-arthritic young hip scores done preoperatively and then at 12 months postoperatively.⁸ Student T Test was used to compare pre and postoperative non-arthritic young hip scores. P value <0.05 was considered to be significant.

3 Results

Nine patients (n = 9) diagnosed with symptomatic benign tumours of the hip joint were included in the study. There were 4 male and 5 female patients with a mean age of 35 years (range 22–43 years). None of the patients have been lost to follow up. No recurrences have been seen in any cases up to a minimum of 18 months follow-up (range 18–48 months). No cases of avascular necrosis have been seen. Four patients have required removal of metalwork due to greater trochanteric bursitis caused by prominent screws. Non-arthritic Young Hip Scores showed significant improvement from a mean of 45 preoperatively to 89 at 12 months (p < 0.001, T Test). Table 1 gives the demographics, clinical presentation, diagnoses and outcome scores of the patients. For the purpose of simplicity further description is given under individual cases.

3.1

3.1 Case 1

A 16-year-old college student presented with groin and medial thigh pain of over 12 months duration. Clinical examination revealed no limitation in hip movements and negative impingement test. Radiographs showed a well-defined lytic lesion in the femoral head and neck (Fig. 1a). CT scan showed the anterior cortex had been breached (Fig. 1b). MRI confirmed a well-circumscribed lesion with no local invasion (Fig. 1c). Surgical dislocation was used and the lesion was curetted completely. The void was filled with morcellized freeze-dried femoral head allograft. A prophylactic compression hip screw was inserted due to cortical breach in the neck. Histology confirmed the lesion to be chondroblastoma. Final radiographs show a well-healed lesion after 36 months of follow-up (Fig. 1d).

Close

Fig. 1 a-c – Radiographs, MRI and CT Scans of chondroblastoma. d. Final radiograph of a healed lesion.

Export to PPT

3.2

3.2 Case 2

A 23-year-old female had a history of rest/night hip pain. Hip movements were limited due to pain and radiographs were unremarkable (Fig. 2a). MRI scan showed mild cam lesion with small “apple core lesions” in the femoral neck (Fig. 2b). She underwent open osteochondroplasty and complete synovectomy. The lesions were found very close to the posterior retinacular blood vessels, which were dealt with careful piecemeal excision of the lesion.

Close

Fig. 2 a–b. Radiograph and MRI scan of case 2 showing “apple core lesions” in Pigmented Villonodular Synovitis.

Export to PPT

3.3

3.3 Case 3

A 31 year old female presented with a one-year history of hip pain. Examination of hip joint showed limited range of motion. Impingement test was positive. Radiographs were essentially normal (Fig. 3a). MRI scan revealed no signs of FAI but thickened synovium and no bony lesions (Fig. 3b). The patient underwent arthroscopy and biopsy, which confirmed PVNS. Surgical dislocation was carried out 2 months later and complete synovectomy was done, preserving the femoral head blood supply.

Close

Fig. 3 a–b. Normal radiograph of case 3 and MRI scan showing synovial hypertrophy.

Export to PPT

3.4

3.4 Case 4

A 41-year-old male presented with clinical signs of impingement syndrome. Radiographs showed mild cam lesion however preoperative MRI scans confirmed the diagnosis of synovial chondromatosis (Fig. 4a and b). The exposure to the joint was satisfactory with easy removal of loose bodies. This was followed by complete synovectomy. It was found that synovectomy around the posterior aspect of the neck was difficult due to proximity of blood vessels supplying the femoral head, however this was managed with careful piecemeal excision of the synovium. Histology showed scattered chondrocytes with calcific deposits in the matrix. No recurrence or AVN has occurred after 34 months of follow-up.

Close

Fig. 4 a–b. Radiographs and MRI scan of case 4 showing synovial chondromatosis.

Export to PPT

3.5

3.5 Case 5

One 43-year-old female presented with a one-year history of right hip pain. Clinical examination revealed a positive impingement (FADIR – Flexion Adduction Internal Rotation) test. Radiographs were normal and MRI scan showed synovial chondromatosis, small cam lesion and degenerate labrum anteriorly (Fig. 5a and b). Ganz approach was used for removal of loose bodies and complete synovectomy. Histology confirmed the diagnosis. The patient has no hip pain after 18 months, however required removal of screws due to greater trochanteric bursitis.

Close

Fig. 5 a–b. Radiographs and MRI scan of case 5 showing synovial chondromatosis.

Export to PPT

3.6

3.6 Case 6

A 19-year-old female presented with 8 months of hip and thigh pain. Hip movements were limited. Radiographs and MRI revealed osteochondroma at the inferomedial aspect of the femoral neck (Fig. 6a–c). Surgical dislocation using Ganz approach provided excellent exposure of the femoral neck and lesion was excised uneventfully. The psoas tendon showed bursa formation, which was carefully excised. Histology confirmed the diagnosis as benign osteochondroma. No recurrence of symptoms has occurred after 48 months of follow-up.

Close

Fig. 6 a–c. Radiographs, CT and MRI scans of case 6 showing osteochondroma femoral neck.

Export to PPT

3.7

3.7 Case 7

A 29-year-old female presented with six months history of hip pain radiating down the thigh. Clinical examination was normal and impingement test was equivocal. Radiographs revealed an osteochondroma at the inferomedial aspect of the femoral neck (Fig. 7a). Further imaging was carried out through CT and MRI scans (Fig. 7b and c). Surgical dislocation using Ganz approach provided excellent exposure of the femoral neck and lesion was excised uneventfully. The psoas tendon and lesser trochanter were inspected but we did not encounter any bursa formation. Histology confirmed the diagnosis as benign osteochondroma. No recurrence of symptoms has occurred after 36 months of follow-up.

Close

Fig. 7 a–c. Radiographs, CT and MRI scans of case 7 showing osteochondroma femoral neck.

Export to PPT

3.8

3.8 Case 8

A 19-year-old female patient presented with 12 months history of nonspecific hip pain. Clinical examination revealed limited range of motion in the hip and negative impingement test. Radiographs showed a well-defined, multiloculated lesion in the proximal femur (Fig. 8a), which was confirmed on MRI scan (Fig. 8b). After surgical dislocation a small cortical window was created in the femoral neck and the lesion was removed. This void was replaced with cancellous allograft from frozen dried femoral heads. A prophylactic compression hip screw was inserted (Fig. 8c). Histology confirmed the lesion to be fibrous dysplasia. Patient has remained asymptomatic until a follow up period of 18 months.

Close

Fig. 8 a,b,c – a–b. Radiograph and MRI Scan of case 8 showing fibrous dysplasia. c. Postoperative radiographs showing compression hip screw and healed lesion.

Export to PPT

3.9

3.9 Case 9

A 25-year-old male was diagnosed with fibrous dysplasia after presenting with 6 months of groin pain. Diagnosis was suspected on pelvis radiographs and MRI scans showed a well-circumscribed lesion in the femoral neck (Fig. 9a and b). Excision was carried out through surgical dislocation uneventfully. Cortical window was created in the neck and excision of the lesion carried out (Fig. 9c). Following complete excision the void was filled with corticocancellous autograft and prophylactic compression hip screw was inserted. Histology confirmed the diagnosis. Patient was asymptomatic after 28 months follow-up.

Close

Fig. 9 a,b,c – a–b. Radiograph and MRI scan of case 9 showing fibrous dysplasia. c. Intraoperative photo showing surgical dislocation of the hip. A cortical window in the femoral neck for excision of the fibrous dysplasia.

Export to PPT

4 Discussion

Surgical dislocation of the hip is a well-recognised approach for treating a variety of hip disorders.^1,3–6 The original series of Ganz et al included 10 cases of benign tumours excised through this approach but no details were described on those cases. Few cases have been reported in the literature where surgical dislocation was used to excise benign tumours around the hip joint.^4–6,9–11 To our knowledge the current series is the first detailed description of various benign tumour excision through the Ganz approach performed by a single surgeon. We have looked at the usefulness of the approach for exposure of the hip joint, risks pertinent to the approach in cases of tumour excision and functional outcome of the patients after surgery at a minimum of 18 months follow-up.

As described by Ganz et al¹ the approach gives excellent exposure to the hip joint. We discovered no significant limitations of the approach. Since the approach utilizes an anterior dislocation of the femoral head, access to the posterior aspect of the hip required extreme adduction and external rotation. Keeping the leg in this non-anatomic position for longer periods could lead to neurovascular damage¹² and hence we advise to return to anatomic position at regular intervals if longer period of access is required to the posterior femoral neck.

In certain cases such as PVNS and synovial chondromatosis where complete synovectomy was required, the authors advise extreme caution in order to protect the blood supply to the femoral head. The retinacular vessels along the posterior aspect of the femoral neck need to be carefully identified and protected before excising the tumour in this area (Fig. 10). The consequence of damage to the blood supply along the posterior aspect of the femoral neck could potentially lead to avascular necrosis. The incidence of avascular necrosis as a consequence of damage to the blood supply during Ganz approach is rare.^1,13 Owing to the rarity of these tumorous conditions it is even more difficult to ascertain the risk of avascular necrosis in such cases. Despite the very low incidence, avascular necrosis is a severe disabling complication of surgery, which is at best avoided by careful excision of synovium. Four cases in our series required synovectomy. No cases of AVN have been seen up to a minimum of 18 months (range 18–48) follow-up.

Close

Fig. 10 Intraoperative photograph of a case of Pigmented Villonodular Synovitis showing blood supply (retinacular vessels) to the femoral head.

Export to PPT

We believe that although visualization of posterior aspect of hip joint is easier with Ganz approach, surgical access could be demanding due to these limitations and therefore surgery should proceed carefully.

Synovial chondromatosis of the hip joint is rare, and the optimal treatment is controversial.¹⁴ Various treatment methods have been described including removal of the loose bodies only, radical synovectomy, open synovectomy with removal of the loose bodies, and an arthroscopic synovectomy with removal of the loose bodies.^11,15,16 Ogilivie-Harris suggested complete or partial synovectomy with removal of loose bodies has low recurrence rates.¹⁷ Lim et al used a modified Watson-Jones approach. They described higher complication rate with open dislocation including one AVN.¹² Recently Schoenigeret al described modified complete synovectomy through surgical dislocation as an effective method of treating synovial chondromatosis. At a minimum follow up of 4 years, the approach proved to be safe with no recurrences.¹¹ No cases of AVN have been described in the literature for treatment of synovial chondromatosis using Ganz approach.^6,10,11

PVNS is a rare, benign, proliferative condition of the synovium involving a joint, bursa, or tendon sheath affecting young age group. Recently a neoplastic origin has been suggested.¹⁸ MRI is the most sensitive and specific modality for diagnosing PVNS.¹⁴ Treatment involves complete synovectomy or total hip replacement. It has been suggested that total synovectomy has low recurrence rate, however it does not prevent progression of arthritis. Considering total hip replacement being the last resort treatment, joint preservation through synovectomy is a reasonably preferable alternative treatment option in young patients.¹⁹

Solitary osteochondromata are less common at the proximal than distal femur.²⁰ Diagnosis is generally made on plain radiographs and MRI is used to assess the thickness of the cartilage cap to differentiate from osteochondrosarcoma.²¹ Treatment is watchful waiting unless lesions become symptomatic through enlargement and pressure effects, or in case of malignant transformation where surgical excision is advised.²² Excision of osteochondromata through Ganz approach has been described previously however no specific details of surgical exposure and risks had been mentioned.¹³ We believe Ganz approach provides excellent exposure for excision of osteochondromata.

Chondroblastoma is a benign lesion of the epiphyseal bone. Radiographically they appear lobulated, with clear sclerotic margins and can vary from small to large sizes up to 10 cm. CT and MRI scans are useful in detailing local anatomy and size of the lesion.²³ These lesions can grow slowly to involve the metaphyseal bone and a minority can extend into local soft tissues. Treatment is generally with curettage and bonegrafting. Surgical approaches for treatment of chondroblastoma of the proximal femur have differed in the past.^24,25 Strong et al reported results of ten cases of chondroblastoma treated with direct open or indirect approach through the femoral neck. The authors concluded that recurrence was less likely through a direct open approach.²⁵ In our case, Ganz approach provided excellent exposure to the femoral head. A cortical window was created in the femoral neck with the lesion curetted and bonegrafted.

In conclusion, Ganz approach with trochanteric slide and anterior surgical dislocation provided excellent exposure to the hip joint and is useful in approaching a variety of benign tumours around the hip joint with protection of the blood supply to the femoral head and minimal complications.

Conflicts of interest

All authors have none to declare.