Healed Legg-Calvé-Perthes disease may cause both intra-articular and extra-articular impingement, resulting in a symptomatic hip prior to the onset of osteoarthritis. Various impingement-relieving surgeries have been used in the past; however, the development of the safe surgical dislocation technique has allowed a better understanding of complex deformity that may be present in these hips and hence may improve treatment of these symptomatic prearthritic hips. This article outlines the range of deformities possible in a Perthes hip, and treatment strategies to surgically address these deformities. For Perthes disease good preoperative clinical and radiographic assessment is essential, and intraoperative assessment vital.
Legg-Calvé-Perthes disease (LCPD) is a pediatric form of osteonecrosis that ultimately heals but can cause femoral head and acetabular deformities. The deformities can be complex and may cause femoroacetabular impingement, hip instability, or combinations of both, and may ultimately lead to degenerative joint disease and early osteoarthritis (OA) of the hip. In the long-term follow-up of LCPD, osteoarthritis is reported to be a direct function of femoral head sphericity and congruence of the joint.
The normal hip is a multiaxial, highly congruent ball-and-socket joint that requires inherent stability to protect and maintain long-lasting articular cartilage function. In addition, it should provide ample and free range of motion required during everyday activities. Instability of the hip is usually a result of acetabular undercoverage, and results in labral tear and cartilage damage at the acetabular rim. Unlike in developmental dysplasia of the hip, in LCPD acetabular dysplasia is a result of secondary acetabular remodeling caused by the aspherical head. Femoroacetabular impingement (FAI) involves abnormal, repetitive contact between the anterior femoral head and/or head-neck junction against the anterior aspect of the acetabular rim, and has been linked to the onset of early osteoarthritis of the hip. While in the unstable dysplastic hip the femoral head can subluxate out of the acetabulum, in FAI the femoral head remains well centered; however, free range of motion is limited. In LCPD, the femoral head may heal in an aspherical shape and may cause both cam and pincer types of impingement. Instability and impingement usually are thought to be distinct pathomechanical entities. However, in LCPD a hip may be unstable in upright activities and yet still impinge in hip flexion due to the aspherical femoral head. FAI in LCPD is most often due to intra-articular impingement from the aspherical femoral head (cam FAI). Nevertheless, it may also be secondary to acetabular overcoverage due to a retroverted acetabulum (pincer FAI). In addition to the deformities caused by the disease process, prior surgical procedure to contain the collapsing head may cause impingement as well. Prior innominate osteotomy or shelf procedure may cause pincer-type impingement. In addition, intra-articular impingement may be caused by functional retroversion of the proximal femur secondary to the retroverted position of the articulating femoral head or secondary to prior femoral osteotomy.
In addition to the two aforementioned mechanical conditions (FAI and dysplasia), the patient with a healed LCPD may present with pain due to abductor fatigue secondary to abductor lever insufficiency (high-riding greater trochanter) and limb length inequality (shorter ipsilateral limb). Osteochondritic lesions in the femoral head, although rare, may also be a source of pain and mechanical symptoms (locking, catching). Therefore, an extensive preoperative evaluation of the proximal femur and acetabular morphology is recommended. The treatment strategy should address all the ongoing mechanical problems that affect each individual hip.
These consequences of residual LCPD deformities have been recognized in the past, and various treatment strategies have been used and reported on in the literature. Impingement of the enlarged femoral head on the lateral lip of the acetabulum, the so-called hinge abduction, is a well-described phenomenon in LCPD. Historically, valgus-extension intertrochanteric osteotomy was indicated for the treatment of hinge abduction. Valgus osteotomy has also been recommended to address residual deformities after the healing phase of LCPD. Myers and colleagues reported on the results of valgus osteotomy in 15 patients who had completed reossification and remodeling of LCPD. There was significant improvement in pain and function measured by the Harris Hips Score after 2 years, and no subsequent alteration at final follow-up at 6.5 years.
Before a femoral osteotomy is performed, a radiograph with the leg adducted should demonstrate improvement of joint congruence, and the location and extension of femoral head deformity should be estimated. Yoo and colleagues postulated that an abnormal hinge movement varies according to whether the impingement is lateral or anterior. These investigators identified some patients in whom major aspherical portion on the femoral head (the so-called bump) was located anteriorly. In this case the classic valgus-extension osteotomy may not be indicated, because the extension component will further add to the anterior impingement.
In saddle-shaped epiphysis, resection of the extruded anterolateral portion of the femoral head (cheilectomy) has been recommended in the past. In 1964 Garceau postulated that “in late Legg-Calvé-Perthes disease osteoarthritic changes resulted from incongruity of the femoral head which, because of bulging on the outer side, impinged on the acetabular lip. The degenerative changes could be reduced or delayed if the head of the femur was remolded. The operation should be done early, preferably before the age of twelve in boys and ten in girls, while remolding could still take place.” Later, McKay and Klisic suggested that cheilectomy should not be performed at an early stage of the disease as had been previously recommended by Garceau. Klisic reported on cheilectomy in children aged 10 years or older. In children with severe subluxated epiphyses, cheilectomy resulted in 75% of ovoid femoral heads with no poor results. Among initially crushed epiphyses, acceptable results (ovoid and round femoral heads) were found after cheilectomy. Rowe and colleagues reported on 5 patients with known poor prognosis who underwent partial head resection (cheilectomy) through an anterior approach. Cheilectomy was effective at reducing pain and improving range of hip motion during the early postoperative years; however, the clinical and radiographic results obtained at 25-year follow-up were not satisfactory. The investigators concluded that cheilectomy was ineffective at preventing the early osteoarthritic changes before age 40 years.
Contemporary approach to residual Legg-Calvé-Perthes deformities
In LCPD, resultant femoral head shape, growth disturbance of the proximal femoral physis, and secondary remodeling of the acetabulum can create complex deformities that may lead to abnormal mechanical function of the hip. With the advent of the safe surgical dislocation approach, clinicians now have an improved understanding of the pathoanatomy in LCPD. The intra-articular and extra-articular pathologies associated with healed LCPD can be classified in the following manner.
Proximal Femoral Pathoanatomy
Residual proximal femoral deformity can be identified as intra-articular, extra-articular, or in both locations. Intra-articular deformity can result from the aspherical femoral head, coxa magna, coxa plana, or a combination of these deformities, and can result in cam impingement, cam-induced impingement, or functional retroversion of the femoral head.
The cam impingement is a result of the aspherical femoral head entering a relatively spherical acetabulum. The acetabulum cannot accommodate the large anterior segment of the femoral head. The anterior deformity can usually be identified on anteroposterior (AP) pelvic radiograph as the “sagging rope sign,” a convex radiopaque line noted on AP plain radiographs of the proximal femur in patients with avascular necrosis of the femoral head. Repetitive injury from the cam impingement can lead to labral injury, progressing to labral avulsion from the acetabular rim, malacia of the acetabular cartilage, and eventual acetabular cartilage delamination.
Cam-induced pincer impingement results from the coxa magna, coxa plana, or a combination of these deformities. The cam lesion (the large anterior femoral head) is too large to enter the joint, thus impinging on the acetabular rim. The cam-induced pincer impingement results in a linear impact of the femoral head on the acetabular labrum causing primary labral injury and acetabular chondromalacia near the rim of the acetabulum. Chronic pincer impingement can lead to labral ossification or a posterior-inferior contra coupe acetabular cartilage injury.
Residual coxa magna may result in the articulating surface of the femoral head being out of line with the femoral neck. The femoral articular surface is frequently in the posteromedial superior portion of the femoral head, adjacent to an anterolateral inferior portion of the femoral head that protrudes from the acetabulum. The anterolateral portion is considered the “false head” that is seen as a “sagging rope sign” and often blocks internal rotation of the hip. The posteromedial portion is considered the “true head” and is the remnant of the original articulating surface. This segment is retroverted relative to the anterolateral segment and results in a “functional retroversion” manifested clinically in an externally rotated gait. The presence of the “false head” can also lead to cam-induced pincer impingement with the resultant labral and acetabular cartilage injury.
Greater trochanteric overgrowth is common in LCPD disease, and should be considered as an extra-articular pathoanatomy causing FAI. The combination of coxa breva (short and broad femoral neck) and high-riding trochanter can lead to anterior and/or posterior trochanteric impingement and represents a “functional coxa vara.” Although the normal femoral neck-shaft angle is maintained, the level of the greater trochanter is cranial to the center of rotation of the femoral head. This situation manifests clinically as abductor weakness and a Trendelenburg limp, identical to that of a patient with true coxa vara.
Coxa breva can also create an abnormal relationship of the lesser trochanter relative to the ischium. Although rare relative to greater trochanteric overgrowth, enlargement of the lesser trochanter and/or decreased ischial-trochanteric distance can result in impingement of the lesser trochanter on the ischium. This impingement can result in pain, a snapping hip, decreased internal rotation of the hip, and/or decreased adduction of the hip.
Acetabular Pathoanatomy
The acetabular dysmorphology that leads to altered hip biomechanics includes acetabular dysplasia, femoroacetabular incongruence, and acetabular retroversion. The steep acetabular roof that is the hallmark of acetabular dysplasia results in insufficient coverage of the femoral head and subsequent joint instability. The instability leads to increased shear stresses across the labrum, acetabular cartilage, and the compromised femoral head cartilage. Consequently, significant labral hypertrophy with or without intrasubstance labral injury and/or labral avulsion from the acetabular rim is frequently identified with associated cartilaginous injury at the acetabular rim.
A misshapen femoral head and acetabulum without true acetabular dysplasia can lead to femoroacetabular incongruity. The femoral head and acetabulum may be mismatched in shape, or the femoral head may be too large for a relatively shallow acetabulum. The incongruity leads to joint instability as a result of a complex motion pattern of femoral head translation and rotation within the acetabulum. Similar to acetabular dysplasia, incongruity and instability leads to increased shear stresses across the labrum and acetabular cartilage.
Acetabular retroversion contributes to impaired hip range of motion and pincer impingement. The cross-over sign identified retroversion of the acetabulum on an AP pelvic radiograph in 31% to 42% of skeletally mature patients with residual deformity of healed LCPD disease. A positive posterior wall sign, indicating a deficient posterior wall, was found in 21% of cases.
All these deformities need to be recognized and their contribution to the patient’s symptoms understood. In addition to the structural deformities, associated intra-articular abnormalities are common and contribute to patient symptoms, and should be addressed on a case-by-case basis; these include acetabular labral tears, articular chondral flaps and chondromalacia, osteochondral lesions, ligamentum teres ruptures, and loose bodies. These abnormalities contribute variably to patient symptoms and are to be addressed surgically on a case-by-case basis.
Clinical presentation and imaging
Symptoms caused by mechanical abnormalities may develop in the residual phase of LCPD, and may cause hip pain in adolescents and young adults who were diagnosed and treated for LCPD as a child. Typically the patient will present with groin pain that is aggravated by physical activities and sitting for long periods. Instability symptoms may present with groin pain after upright activities such as walking and running. Impingement symptoms are more common in positions of hip flexion and internal rotation. Early on, symptoms may be more characterized as stiffness and limitation of motion rather than pain. Mechanical symptoms of locking and catching may indicate the presence of intra-articular diseases including labral tears, chondral flaps, or an unstable osteochondral fragment.
Initial imaging should include an appropriate AP pelvic plain radiograph that can be obtained with the patient standing or supine. Quantitative measurements of acetabular coverage on the AP pelvis include the lateral center-edge angle of Wiberg and the acetabular index of Tönnis. The presence of a break in Shenton’s line of greater than 5 mm characterizes joint subluxation and is a sign of mechanical instability of the hip. Acetabular retroversion can be identified by the presence of a cross-over sign and the projection of the ischial spine into the pelvis. The depth of the acetabulum can be evaluated using the ilioischial line as a reference: if the floor of the fossa acetabuli touches or is medial to the ilioischial line the hip is classified as coxa profunda, and if the medial aspect of the femoral head is medial to the ilioischial line it is classified as protrusio acetabuli. In general, coxa profunda is rare in LCPD. Careful technique and analysis of the AP pelvis radiograph is important, as increased spinopelvic lordosis and pelvic rotation may falsely make the acetabulum appear retroverted. In LCPD hip flexion contracture may be present, which may make the pelvis appear rotated or in a more lordotic position; therefore, interpretation of acetabular retroversion often needs to be interpreted with caution in LCPD. In addition to the pelvic radiograph, a false profile view of the acetabulum should be obtained to look for anterior undercoverage of the femoral head.
A lateral view of the proximal femur (cross-table lateral, frog-leg lateral, or a Dunn view ) should also be obtained. The lateral view of the proximal femur adds information about the sphericity of the femoral head and the reduced head-neck offset. Quantitative evaluation of the head-neck junction includes measuring the alpha angle and the head-neck offset ratio. Functional radiographs, with or without an arthrogram, can provide additional information regarding the indication of a realignment femoral osteotomy in nonspherical hips.
Accurate measurement of acetabular and femoral version can be important information needed in the treatment planning of LCPD, and may require advanced imaging modalities such as computed tomography (CT) and magnetic resonance (MR) imaging. In LCPD, the anterolateral extrusion of the enlarged femoral head is believed to block internal rotation, while the posteromedial superior portion of the head that truly articulates in the acetabulum is retroverted and may functionally cause retroversion of the proximal femur. CT scanning helps to quantify the femoral head-neck concavity and has the advantage of 3-dimensional reconstruction, although it requires a dose of radiation. MR arthrography with radial cuts rotating around the femoral neck axis allows assessment of the femoral head-neck junction shape and the labrum in its entire circumference. Recently, delayed gadolinium-enhanced magnetic resonance imaging of cartilage has allowed direct assessment of cartilage matrix, and understanding of the complex damage pattern of hip joint cartilage and labrum after LCPD.
Clinical presentation and imaging
Symptoms caused by mechanical abnormalities may develop in the residual phase of LCPD, and may cause hip pain in adolescents and young adults who were diagnosed and treated for LCPD as a child. Typically the patient will present with groin pain that is aggravated by physical activities and sitting for long periods. Instability symptoms may present with groin pain after upright activities such as walking and running. Impingement symptoms are more common in positions of hip flexion and internal rotation. Early on, symptoms may be more characterized as stiffness and limitation of motion rather than pain. Mechanical symptoms of locking and catching may indicate the presence of intra-articular diseases including labral tears, chondral flaps, or an unstable osteochondral fragment.
Initial imaging should include an appropriate AP pelvic plain radiograph that can be obtained with the patient standing or supine. Quantitative measurements of acetabular coverage on the AP pelvis include the lateral center-edge angle of Wiberg and the acetabular index of Tönnis. The presence of a break in Shenton’s line of greater than 5 mm characterizes joint subluxation and is a sign of mechanical instability of the hip. Acetabular retroversion can be identified by the presence of a cross-over sign and the projection of the ischial spine into the pelvis. The depth of the acetabulum can be evaluated using the ilioischial line as a reference: if the floor of the fossa acetabuli touches or is medial to the ilioischial line the hip is classified as coxa profunda, and if the medial aspect of the femoral head is medial to the ilioischial line it is classified as protrusio acetabuli. In general, coxa profunda is rare in LCPD. Careful technique and analysis of the AP pelvis radiograph is important, as increased spinopelvic lordosis and pelvic rotation may falsely make the acetabulum appear retroverted. In LCPD hip flexion contracture may be present, which may make the pelvis appear rotated or in a more lordotic position; therefore, interpretation of acetabular retroversion often needs to be interpreted with caution in LCPD. In addition to the pelvic radiograph, a false profile view of the acetabulum should be obtained to look for anterior undercoverage of the femoral head.
A lateral view of the proximal femur (cross-table lateral, frog-leg lateral, or a Dunn view ) should also be obtained. The lateral view of the proximal femur adds information about the sphericity of the femoral head and the reduced head-neck offset. Quantitative evaluation of the head-neck junction includes measuring the alpha angle and the head-neck offset ratio. Functional radiographs, with or without an arthrogram, can provide additional information regarding the indication of a realignment femoral osteotomy in nonspherical hips.
Accurate measurement of acetabular and femoral version can be important information needed in the treatment planning of LCPD, and may require advanced imaging modalities such as computed tomography (CT) and magnetic resonance (MR) imaging. In LCPD, the anterolateral extrusion of the enlarged femoral head is believed to block internal rotation, while the posteromedial superior portion of the head that truly articulates in the acetabulum is retroverted and may functionally cause retroversion of the proximal femur. CT scanning helps to quantify the femoral head-neck concavity and has the advantage of 3-dimensional reconstruction, although it requires a dose of radiation. MR arthrography with radial cuts rotating around the femoral neck axis allows assessment of the femoral head-neck junction shape and the labrum in its entire circumference. Recently, delayed gadolinium-enhanced magnetic resonance imaging of cartilage has allowed direct assessment of cartilage matrix, and understanding of the complex damage pattern of hip joint cartilage and labrum after LCPD.
Surgical treatment techniques
Periacetabular Osteotomy
Since its original description by Ganz and colleagues, the Bernese periacetabular osteotomy (PAO) has gained popularity in the treatment of acetabular dysplasia. The rationale and technique of PAO in patients with major aspherical femoral heads has been recently revised. The goal is to mechanically stabilize the dysplastic hip, reducing acetabular rim loading to physiologic levels, and to avoid creating FAI. Clohisy and colleagues recommended that a minimum of 95° of hip flexion should be present preoperatively as acetabular reorientation reduces hip flexion and abduction motion. The procedure is performed with the patient in the supine position. A modified Smith-Petersen anterior approach is recommended to avoid extensive damage to the abductor musculature. Subperiosteal dissection of the inner table of the ilium is performed. Distally, the tensor fasciae latae compartment is entered and the sartorius identified. The lateral femoral cutaneous nerve within the sartorius fascia is therefore protected. The anterior-superior iliac spine (ASIS) is osteotomized or the sartorius is detached with a thin wafer of bone. With the leg in flexion and adduction, the reflected head of the rectus femoris is divided and the direct head of the rectus is elevated together with the iliocapsularis muscle from the hip capsule. The interval between the capsule and the iliopsoas tendon is developed and the osteotomy of the anterior portion of the ischium is performed. Osteotomy of the superior pubic ramus just medial to the iliopectineal eminence is then performed with a Gigli saw passed around the obturator foramen, with a microsagittal saw or with regular osteotomes. The supra-acetabular iliac osteotomy is performed with an oscillating saw aiming toward the apex of the sciatic notch and ending about 1 cm above the iliopectineal line. This corner will serve as the starting point of the posterior column osteotomy that is performed next. A Shanz screw is inserted into the acetabular fragment and is used to help mobilize the fragment into the corrected position. Anatomically, the goal is to reorient the acetabular sourcil to nearly horizontal and restore the Shenton line, without lateralization of the hip center of rotation and no retroversion of the acetabulum (no cross-over or posterior wall sign). The acetabular fragment is then fixed with either 3.5- or 4.5-mm cortical screws. The osteotomy cuts, positioning, and fixation are monitored with intraoperative fluoroscopy. At this point an anterior arthrotomy is performed to inspect the acetabular labrum (and treat unstable labral tears) and to assess the femoral head-neck junction. In healed LCPD the large aspherical femoral head usually impinges against the acetabulum. An osteochondroplasty of the femoral head-neck junction is performed to optimize impingement-free range of motion. The capsule is closed and the rectus femoris and ASIS are repaired. The wound is closed in layers over a Hemovac drain.
Surgical Dislocation of the Hip
The surgical hip dislocation approach was initially described by Ganz and colleagues after performing a dedicated study of the blood supply of the femoral head. This approach allows complete access to the femoral head and acetabulum without risk of avascular necrosis of the femoral head. The procedure is performed with the patient in the lateral decubitus position. The entire lower extremity is prepped and draped, allowing visualization of the ASIS and the posterior superior iliac spine (PSIS), as they will serve as bony landmarks. A straight lateral incision (approximately 20 cm in length) is performed. In the past a Kocher-Langenbeck approach was used (splitting the muscle fibers of the gluteus maximus); however, nowadays a Gibson approach is preferred (the anterior muscle fibers of the gluteus maximus are freed from the fascia and the muscle is retracted posteriorly without splitting it). The fascia lata is split in line with the femoral shaft, exposing the vastus lateralis ridge and the posterior border of the gluteus medius. At this point the authors favor mobilizing the gluteus medius anteriorly and exposing the piriformis tendon. The interval between the piriformis tendon and the gluteus minimus is opened by sharp dissection. The inferior border of the gluteus minimus is dissected from underlying capsule. Performing this initial dissection will facilitate the exposure of the hip capsule further in the procedure. It is important to stay above (proximal to the superior border) the piriformis tendon to avoid injury to the anastomosis between the inferior gluteal artery and the medial femoral circumflex artery (MFCA). Next, a 1- to 1.5-cm thick trochanteric osteotomy is performed with an oscillating saw, leaving the piriformis tendon and short external rotators intact on the base of the stable trochanter. The trochanteric piece is reflected and flipped anteriorly with the attached vastus lateralis and gluteus medius. The previously exposed capsular minimus is further elevated anteriorly off the hip capsule. The anterolateral portion of the vastus lateralis is released from the femur, with the hip in external rotation until the level of the gluteus maximus insertion. A capsulotomy is performed in a Z-shape fashion (right hip) or reverse Z-shape (left hip), with the longitudinal arm of the Z in line with the anterior femoral neck. The distal capsulotomy extends anterior proximally to the lesser trochanter while the proximal cut is performed along the acetabular rim until the piriformis tendon. With the capsule opened, the hip is carried through a range of motion with special attention to flexion and internal rotation. At this point, intra-articular and extra-articular causes of FAI can be dynamically determined. Flexion, adduction, and external rotation subluxates the hip, and the ligamentum teres is divided to allow complete dislocation of the femoral head. Three Hohman retractors are placed around the acetabulum, allowing complete exposure. The acetabulum articular cartilage and the labrum are inspected for the presence of labral and chondral lesions. The deformity of the femoral head (cam component) is accessed using spherical templates. Any nonspherical portion of the femoral head is removed with an osteotome and a burr. Reduction of the femoral head after osteochondroplasty should reveal improved flexion without impingement. If an osteochondroplasty is all that is required then the capsule is closed loosely and the trochanteric fragment is fixed with 2 or 3 3.5-mm cortical screws.
Development of Retinacular Soft-Tissue Flap: Relative Lengthening of the Femoral Neck and Femoral Head Reduction Osteotomy
In cases of healed LCPD the severity of the deformity (high-riding greater trochanter and short femoral neck) requires that osteochondroplasty of the femoral head-neck junction be performed in combination with a relative lengthening of the femoral neck (RLFN). The goals are to not only to improve abductor muscle function, but more importantly to correct the extra-articular source of impingement caused by the short femoral neck. Rarely, in extreme cases in patients between 10 and 15 years of age with no other surgical alternative, a resection of the middle portion of the persistently necrotic femoral head (femoral head reduction osteotomy [FHRO]) may be indicated in healed LCPD. The ideal indication is the patient who has restricted motion secondary to a large femoral head, whose peripheral cartilage is good but has a central segment of the head that has poor articular cartilage. In these situations an extended retinacular soft-tissue flap should be developed to protect the blood supply to the femoral head.
To develop the retinacular flap, the femoral head should be reduced into the acetabulum. The first step is to trim the posterosuperior portion of the stable greater trochanter down to the level of the femoral neck. The greater trochanter physis is identified. The portion of the greater trochanter proximal to the growth plate is mobilized with an osteotome, and the cancellous bone carefully removed from the periosteum. The periosteum is incised along the anterior neck beginning at the anterosuperior corner of the greater trochanter growth plate. The periosteum of the neck, including the retinaculum with the blood vessels and the external rotators, is gradually released. For RLFN the flap does not have to be developed in the whole circumference, as with FHRO. After the retinacular flap is developed the superior contour of the stable trochanteric segment is further trimmed in line with the femoral neck. The capsule is closed without tension. The mobile trochanter is advanced distally and fixed with 2 or 3 3.5-mm cortical screws.
Resection of the central portion of the femoral head (FHRO) is deemed possible because the extended retinacular flap preserves the blood supply to the superior portion of the femoral head. An additional branch of the medial circumflex femoral artery runs within the Weitbrecht ligament and supplies the inferior portion of the head. The retinacular flap is extended posteriorly along the femoral neck while leaving it secured to the epiphysis. The lateral cut in the head/neck is made in line with the axis of the femoral neck, with a distal transverse cut made to allow mobilization. The medial cut is then made parallel to the first cut, and the segment is removed, allowing the remaining portions to be anatomically reduced. Two or 3 3.5-mm cortical screws are inserted from lateral/superior to medial/inferior.
Femoral Osteotomy
Valgus intertrochanteric osteotomy may be performed in isolation, but more often it is now performed in conjunction with a surgical dislocation approach to address intra-articular pathologies. Preoperative planning is mandatory to calculate the amount of valgization and the appropriate hardware to be used. In addition to valgus, flexion/extension and internal/external rotation may be added to the osteotomy. In LCPD the femoral head may be in a retroverted position, therefore a valgus/internal rotation osteotomy may be indicated.
Greater Trochanter Advancement and True Femoral Neck Lengthening
Several different techniques have been reported for the transfer of the greater trochanter. These methods include isolated transfer of the osteotomized fragment of the greater trochanter distally or a trochanteric transfer combined with a proximal femoral osteotomy. Wagner described the double osteotomy, using the base of the greater trochanter to lengthen the femoral neck and distally transferring the greater trochanter. The Morscher double osteotomy involves removing a segment of bone from the greater trochanteric base that is interposed between the trochanter and the femoral shaft. The distal osteotomy is at the subtrochanteric level and its angle corresponds with the desired neck-shaft angle. These osteotomies create several moving pieces, and internal fixation may be technically difficult. At present, relative neck lengthening is thought to be more effective than trochanteric transfer, due to the fact that in addition to the distal transfer, the extra-articular impingement around the large trochanteric base is visualized and surgically treated.
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