Legg Calve Perthes disease
Legg-Calve-Perthes disease (LCPD) is a hip disorder during the childhood believed to be the resultant of a disruption of the vascularization to the head of the femur. A lack of blood flow, responsible of the fact that the proximal femur stops growing and the bone dies in a process called “Avascular Necrosis” or “Osteonecrosis”. Later, a regeneration of the vasculature will assure a neo-vascularization in infiltrating the necrotic bone and bringing new bone formation. A reduction in the bone mass may weaken the femoral head during the formation of the new blood supply.
Commonly seen in young children between the ages of 4 and 8, but in a broader period between the age of 2 and 15, permanent deformities of the proximal femur may happen to the one suffering from the disease to a point that they may develop later degenerative arthritis in the adulthood. This disease is considered as a form of ‘Osteochondritis’ which can affect one or both hips. This condition can be found synchronously but relatively symmetrical and bilateral. In this circumstance, one should be alerted on searching for other etiologies like multiple epiphyseal dysplasia. LCPD ranges from 5.5 to 15 cases per 100,000 children of age 0 to 14 years in a study by Joseph in 2003 and also vary according to the socioeconomic status, geography, race and even education level. The disease is not well understood but several factors play a role. Studies have demonstrated that an ischemia may due to coagulopathies as explained by Stulberg (1981) decreasing the arterial and venous drainage… A hereditary cause has also been suggested in small familial subsets where a type 2 collagen gene defect was found, affecting children with shorter stature especially involving the lower extremities (Vosmaer) and also associated with attention deficit like ADHD (Burwell 1988).
Common symptoms are related to hip and knee pain and even ankle pain exacerbated through any range of motion of the lower extremity especially when internal or external rotation as well as abduction are looked for. The symptoms are worsening with activities and improving with rest and non-steroidal anti-inflammatories medications. A flexion contracture of the hip is first seen (Thomas test) and limitation of abduction and internal rotation. As the disease progresses, an adduction contracture may develop. The patient may ambulate with a typical limp because of the atrophy of the thigh muscles following the lack of activity of the involved extremity. An antalgic gait is frequently seen with shortened stand phase when early weight bearing shift off on the affected side. Often there is also a leg length discrepancy with possible signs of irritation or inflammation of the affected hip joint. Standing, Running, Kneeling or Stooping activities may increase the symptoms of pain especially when the osteonecrosis becomes severe. With more severe involvement, deformation of the hip joint, symptoms of impingement and restricted range of motion will develop as well. The acetabular side can become involved, showing chondral lesions while the femoral head exhibit osteochondral defects. The more severe the deformities, the greater the chances in developing degenerative arthritis.
The child will complaint of soreness and often we may have a tendency in dismissing the symptoms as growing pain. Limping will follow or at least guarding of the joint can be observed. We have already demonstrated the way such patient can feel pain in the knee. It is described as a referred pain but can occasionally can be referred to the unaffected lower extremity. Predominantly, the disease affects the male/female to a 4 to 1 ratio although the disease is often diagnosed between 5 to 12 years of age. Some cases have been reported as early as 18 months. Bilateralism of the hip involvement can be observed in 10% of cases.
The disease was first described in 1897 by Karel Maydl (1853-1903), then in 1909, Henning Waldenstrom (1877-1972) attributed the changes found in the disease to tuberculosis but in 1910, the disease was recognized as being unrelated to tuberculosis by three physicians: Arthur Legg (1874), Jacques Calve (1875) and Georg Perthes (1869-1927). Legg came with the explanation that the blood supply was impaired at the femoral epiphysis. Calve compared it to Rickets and Perthes suggested that an infection may have been the reason leading the degenerative changes. Nowadays, the disease is explained by the disruption of the blood supply to the femoral head with subsequent osteonecrosis and a delayed in growing. Other factors have been implicated from Trauma to Heredity to endocrine dysfunction or inflammatory changes. Even poor nutrition, delay in in skeletal maturity and finally defective vascularization have been blamed to explain the pathology.
The blood supply to the femoral head comes at a young age from the “ligamentum teres femori” artery which may become constricted not allowing the medial circumflex to take over the blood supply to the femoral head. Legg Calve Perthes disease becomes a restrictive vascular condition, idiopathic in nature. The symptoms will depend on the changes in the femoral head going from deformation, flattening and finally collapse encountered as early as four to ten years, during the period in which the disease can be observed predominantly in male Caucasian. Children often display an uneven gait with a poor range of motion. They will progressively develop groin pain and the child will experience a decrease in the bone strength with pathologic changes in the hip joint. Genetics do not appear to play a role but it is believed that a deficiency in the blood factors can disperse clots allowing blockage of the vessels supplying the joint. Protein C and Protein S which act as blood anticoagulant may promote by their absence, clot formation in the ligamentum teres femori artery. Further researches are needed.
A neovascularization will develop infiltrating the dead bone to remove the necrotic bone, leading to a loss in the bone mass and a new femoral head but weaker. Collapse and deformity may follow affecting the hip socket resulting in an idiopathic avascular necrosis of the femoral epiphysis due to the interruption of the blood supply. Permanent deformity can be also expected with a high risk in degenerative arthritis. This is the reason why Perthes disease is considered as an ‘Osteochondritis’ similar to the one encountered at the knees, ankles, elbows or feet. In any case of bilateralism of the disease, one has to investigate the possibility of a case of multiple epiphyseal dysplasia.
The disease lead to a variable degree of permanent femoral head deformity. Distinct radiologic stages were described by Waldenstrom with an initial phase of induced ischemia followed by a phase of fragmentation where a fibro-vascular invasion takes place bringing physeal changes and cartilaginous metaplasia. An apparent lysis of the epiphysis as well as the metaphysis is then noted with variable collapse. Finally, a phenomenon of re-ossification takes place while the fibro-vascular tissue and the cartilage islands are replaced by woven bone until their full replacement by normal bone. This classification of Waldenstrom can be useful in the treatment. Other radiologic classifications like the “Salter-Harris Classification”, the “Catterall classification” or the “Lateral Pillar classification” have been useful in estimating the severity of the disease and in providing guidelines for a better outcome, will be explained soon. Radiographic studies usually demonstrate a flattened or a fragmented femoral head. Bone Scan or MRI can be more assertive in the diagnosis. The MRI studies appear to be of better help in an early detection of the disease, up to 99% of cases. Bone scan can be also beneficial demonstrating patchy areas of vascularity in the capital femoral epiphysis. These stages of the disease are expected to last less than two years. Let us review the radiologic classifications by imaging studies:
1- The Salter-Harris Classification: Based on the extend of the subchondral bone involvement in the late stage on AP and Frog leg views. If you have less than 50% head involvement, the diagnosis is good.
2- The Catterall classification is based on the extend of the subchondral fracture in the late initial stage: anterior epiphysis, anterior and central epiphysis, all the head except the lateral epiphysis, entire epiphysis. With this classification we can appreciate the subluxation of the head laterally. A “V” shape defect laterally presenting as a lucency is called the “Gage sign”.
3- The lateral Pillar classification (Herring) looks at the lateral 1/3 of the femoral head during the late fragmentation and searching for a loss of height of more or less than 50%.
Those three classifications depend on the extend of the disease and the expertise of the reviewer. A last classification is the modified Elizabethtown classification of Waldenstrom which appreciate the stage of the disease like sclerosis and no loss of height, sclerosis and loss of height, Early fragmentation, advanced fragmentation, early porotic new bone formation at the periphery and finally complete healing.
The main goal of the treatment is to decrease pain and prevent further deformity in restricting the range of motion and the weight bearing. The younger the patient the better the prognosis for recovery. The goal in LCPD is to achieve a spherical femoral head in a concentric joint once the disease process is over based on the radiological findings. Historically, avoiding mechanical pressure on the joint was necessary until the disease runs its course. Traction on the lower extremities was imposed to avoid weight bearing, braces were prescribed for months to facilitate range of motion. Physical therapy has kept an important place in the treatment of Legg Calve Perthes disease and focused on maintaining hip range of motion specially abduction. Containment treatment to keep the femoral head in the acetabulum in order to prevent deformity. Non-operative treatment can be achieved through plaster casting or abduction braces. A frame orthosis or Custom prosthetics as well as overnight traction devices have become popular in the treatment abducting the lower extremities to 45 degrees in keeping the extremity internally rotated. The orthoses can include the lumbar spine and extend to the length of the lower extremity. The Scottish Rite Orthosis has been in the past very popular but it uses has gone out of favor.
Older children above the age of 6, need no intervention but need to refrain from contact sports. Older children may require prolonged periods without any weight bearing and even surgical treatment. Osteotomy on the proximal femur or on the pelvis as well as hip distraction methods with external fixators have been used to avoid weight bearing while the proximal femur is allowed to regrow. Running and high impact sport activities are not recommended. Swimming is highly recommended to keep the hip muscles functional while stress is reduced to the minimum. Cycling activities are encouraged. Daily exercises under physiotherapy supervision has helped in the management of the disease, facilitating the healing process of the femoral head in the hip socket. Others have implemented the use bisphosphonate to facilitate the remodeling of the femoral head. Legg Calve Perthes is a self-limiting disease and if the femoral head if left deformed, long term problems are expected.
The younger the patient the better is the prognosis and the better are the chances in having the femoral head re-vascularize and remodel to a near normal shape. Younger than 8-year-old patients with the disease will do well with conservative treatment but children of an older age past 10 carry a high risk in developing osteoarthritis as well as deformity like “coxa magna”.
Surgical containment can be achieved through a varus femoral osteotomy at the intertrochanteric area or via pelvic osteotomy. The surgical treatment will look at the age of the patient at onset of the disease and the radiologic signs to decide on the proper technique. Valgus osteotomies can be also taken out in the late stages after residual deformation of the epiphysis. Patients with these deformities in a healed LCPD may suffer from impingement or acetabular dysplasia. Arthroscopy has been used to manage the femoro-acetabular impingement as well as “Osteochondroplasty” of the head and neck via an arthrotomy of the hip joint. Other cases may benefit from a pelvic osteotomy especially a peri-acetabular osteotomy in face of acetabular dysplasia. Those represent salvage procedures to render the hip more functional during the healed phase. Then, when the disease run its course and symptoms of pain due to an advanced degenerative arthritis impending on the ability to ambulate, a joint replacement, past the age pf 50’s can be offered to alleviate discomfort.
Legg-Calve-Perthes is one of the most common hip disorders in young children representing 5,5 of 100,000 children a year and the risk for a child to develop the disease is about one per 1200 individuals. The boys are affected four times more than girls and cases rarely occur after the age of 14. But if a 14-year-old adolescent is discovered with the disease, it is surely somebody who have experienced long-standing discomfort for years since his childhood. Northern Europeans appear to be affected more frequently but nobody has yet proven that Legg Calve Perthes disease has any genetic predisposition. No environmental factor has been described but deprived communities may have a greater risk of showing the disease. Tobacco smoke exposure has been also suggested.
The British Orthopedic Society started collecting data on the disease in 2016 and all hospital in the country have collected information on each case. This study is supported by the Perthes’ Association in UK and funded by the National Institute of Health Research and the Alder Hey Charity. The prognosis is judged by the risk of developing degenerative arthritis which can be also judged by another radiologic classification of Studlberg where the shape of the head of the femur in the acetabulum is evaluated from a spherical to a fully deformed and arthritic joint. Recently, perfusion MRI has been added as a tool to determine the stages of the disease with a good prognosis value.
Legg-Calve-Perthes disease has been discovered in small breed dogs and the pathology was well described in the veterinarian literature by Tult in 1935 with no sex predilection but a 15% incidence of bilateral disease. Those dogs are affected between the age 4 and 12 months and conservative treatments like rest and exercises or surgical treatments like removal of the femoral head have offered relief. Prednisone is recommended but the prognosis is excellent with this approach.
Maxime Coles MD
Boca Raton FL
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