Developmental hip dysplasia, formerly known as congenital hip dislocation, is a general term for a group of pathologies characterized by spatial and temporal instability of the hip joint during development, including hip dislocation, subluxation, and acetabular dysplasia.DDH can cause abnormal gait, abnormal development of adjacent joints, and secondary deformities of the spine in children, leading to lower back pain and pain due to degenerative hip degeneration in adulthood. Because the disease is closely related to the developmental process of the hip joint, the presentation and corresponding treatment varies among age groups.
The goal of DDH treatment is to obtain stable concentric repositioning and avoid ischemic necrosis (AVN) of the femoral head. Early diagnosis and treatment are the keys to improve the outcome.
(I) Birth to 6 months
This stage is the prime time for DDH treatment, with simple and easy method, good compliance, reliable efficacy and few complications.
1. Clinical manifestations and signs: asymmetry of thigh skin pattern and hip pattern, joint popping and unequal length of lower limbs. Ortolani/Balow sign is positive. Inequality of limbs, positive Allis (Galleazzi) sign, etc.
2.Imaging: Ultrasound examination of the hip joint is preferred for children ≤4 months old, Graf method; X-ray double hip orthopantomographs can be taken for children >4 months old, commonly used indicators are Perkin’s square, acetabular index (AI), central marginal angle (CEA), Shenton line, teardrop (Teardrop) sign.
3.Treatment: Prefer Pavlik retractor, maintain hip flexion 100°~110°, abduction 20°~50°. 24 hours maintenance. Prohibit dislocation movements (including examination and clothing change). Regular ultrasound examination, 1 time/1~2 weeks. If ultrasound suggests obtaining concentric repositioning after 3 weeks, continue maintenance for 2 to 4 months. An abduction brace was then used until the acetabular index (AI) was <25° and the central marginal angle (CEA) was >20°. If after 3 weeks ultrasound and clinical examination suggest that no repositioning has been achieved, the Pavlik brace is discontinued and other treatment is used instead. Otherwise, persistent compression of the posterior wall of the acetabulum by the posteriorly dislocated femoral head may lead to retention disease (dysplasia of the posterior acetabular wall). Other treatment methods include bracing (fixed in the same position as the brace) or direct closed-replacement plaster fixation. Non-anesthesia repositioning and wearing extreme (frog) abduction brace are contraindicated to avoid damage to the femoral head cartilage and AVN.
(II) 7 months～18 months
With the increase of age, weight and activity increase, the compliance and efficacy of using the retainer decreases.
1. Clinical manifestations and signs: In addition to the above manifestations, physical examination reveals asymmetric appearance of both hips, wide perineum, high greater trochanter, positive telescope sign (telescope sign) and Allis sign.
2.Imaging: X-ray orthopantomogram of both hips is the main examination, and the evaluation index is the same as above.
3. Treatment: Closed repositioning under anesthesia and plaster tube fixation in human position are preferred. Before closed repositioning, the internal longus muscle should be cut or percutaneously, and if necessary, the iliopsoas tendon should be cut at the same time, and repositioned by gentle Ortolani technique. The observation index is safe zone >20°. Arthrography with Onyepek is recommended. If the angiogram shows a gap between the cartilage margin of the femoral head and the inner wall of the acetabulum >4 mm, it suggests soft tissue impaction between the head and socket, blocking the reset. Abandon closed repositioning and use transmedial approach (Ludolff, Ferguson) or anterolateral approach (Bikini, S-P) to perform incisional repositioning instead. Preoperative skin traction is possible for 1 to 2 weeks, or for several weeks to achieve repositioning.
After repositioning, the hip is fixed in a human plaster cast for 100° of flexion, 40-50° of abduction, and neutral rotation for 3 months, and then the cast is replaced and continued to be fixed in a plaster cast or brace for 3-6 months.
At the end of the above treatment, the sick child has the following conditions.
① Concentric repositioning of the head and socket and observation; films are taken once every six months;
(ii) The head socket is repositioned, but the residual acetabulum is dysplastic, manifested by steep and straight acetabulum with AI>24°, but the Shenton line is continuous, and an abduction brace is worn, especially at night; films are taken every 4 months to observe the improvement of acetabular inclusion (AI, CEA), or the appearance of subluxation;
(iii) Residual subluxation, which is manifested by discontinuity of the Shenton’s line, is usually associated with acetabular dysplasia. An abduction brace may be worn and the patient should be reviewed every 3 months for a total of 6 to 12 months. If there is persistent subluxation (interruption of the Shenton’s line), surgical correction should be performed; if it continues to improve, the treatment should be the same as ②;
④ For residual AVN, the affected femoral head should be placed under the inclusion of the acetabulum to allow for repair and shaping.
The specific treatment is the same as ② and ③.
(C) 18 months~8 years old (walking age)
1. Clinical manifestations and signs: limp, duck walk; unequal lower limbs, increased lumbar lordosis, restricted hip abduction, positive Allis sign, positive Trendelenburg sign, etc.
2.Imaging: X-ray double hip orthopantomographs, assessment indexes are the same as before. CT 3D reconstruction is an effective means to observe the anterior femoral tilt angle and posterior dislocation.
3.Treatment: It is still possible to try closed repositioning within 2 years of age, but most children need incisional repositioning and osteotomy. Osteotomy of the pelvis and proximal femur not only corrects the deformity of the acetabulum and proximal femur itself, but also provides stability after reset.
Currently, the common international treatment is one-stage surgery: incision and repositioning, pelvic osteotomy, and proximal femoral osteotomy. Preoperative traction is not required.
(1) Incisional repositioning: anterolateral S-P or Bikini approach. The main points are: full exposure, release, T-shaped incision of the joint capsule, removal of the socket contents (round ligament, transverse glenoid ligament, avoid excision of the glenoid lip), the head is also incorporated into the true socket to achieve concentric repositioning, and V-shaped joint capsule tightening and molding.
(2) Pelvic osteotomy selection: Any kind of pelvic osteotomy cannot treat DDH, and the basic preoperative requirement is that concentric repositioning has been achieved. Reconstructive pelvic osteotomy should be preferred.
(3) Proximal femur (inter-rotor and subrotor) shortening osteotomy is to reduce the intercranial pressure and avoid AVN; rotational inversion osteotomy is to correct the excessive anterior tilt angle and neck stem angle.
Postoperatively, the hip was fixed in herringbone plaster for 6 weeks. In children over 5 years old, to prevent joint stiffness, plaster fixation was feasible for 3 weeks followed by bilateral lower extremity abduction skin traction for 3 weeks. X-ray examination was performed to confirm the healing of the osteotomy, the absence of AVN and the resumption of walking. The hip joint development should be reviewed annually until bone maturity.
(IV) Above 8 years old (older DDH)
1. Clinical manifestations and signs: In addition to the above manifestations, attention should be paid to the presence or absence of fatigue pain and (in children with subluxation) end-of-motion extrusion pain of the joint.
2.Imaging: X-ray orthopantomographs of both hips, the same evaluation indexes as before, and the presence or absence of osteoarthritis in the semi-dislocated joint should be noted. 3D CT reconstruction can also evaluate the morphological adaptation of the head socket in addition to observing the anterior tilt angle and posterior dislocation.
3. Treatment: there is controversy. The aim of treatment for unilateral dislocation is to maximize the restoration of anatomy and function and to create conditions for joint replacement. Equalization of lower limb length prevents secondary spinal deformity. The prognosis of surgical complications in bilateral dislocation without pseudosocket formation is inferior to the natural prognosis, and treatment can be abandoned. Bilateral dislocation with pseudosocket formation is prone to early onset of osteoarthritis, and palliative treatment is feasible.
The common procedures for palliative treatment (abandonment of repositioning) are internal pelvic displacement osteotomy (Chiari procedure), acetabular expansion (slot extension, Staheli), and Shanz osteotomy (subrotor abduction osteotomy).
The surgical treatment of older DDH has poorly defined indications, difficult surgical operations, many surgical complications, and uncertain efficacy, so it should be used with caution and with the participation of an experienced and dedicated surgeon.
(E) Diagnosis and treatment of acetabular dysplasia
It can be seen in all age groups and can be primary or secondary (after closed/incisional repositioning).
1, clinical manifestations and signs: mostly asymptomatic, late stage may have fatigue or pain in the hip. Few positive signs are present, but end-of-motion pain should be noted, suggesting glenoid labral injury.
2.Imaging: X-ray orthopantomogram of both hips with CEA <20° and cephalic socket coverage <80%, Faux posture (pseudo-lateral) film to understand the development of the anterior border of the acetabulum, CT 3D reconstruction.
3.Treatment.
Acetabular dysplasia has the potential to improve with development. If there are no imaging changes of early osteoarthritis and/or subluxation, close follow-up observation is possible. If there is no improvement and early osteoarthritic changes appear, external osteotomy of the joint capsule should be performed. In case of subluxation (Shenton’s line interruption), additional orthopantomographies of both hips (≥20°) should be taken, and if central repositioning is possible, external osteotomy should be performed; if central repositioning is not possible, incision and repositioning with osteotomy should be performed.
The choice of osteotomy site and procedure is based on whether or not central repositioning is possible, the adaptation of the head and socket, and the developmental potential.
Obvious maladjustment of the cephalic socket, large socket and small head: acetabuloplasty.
Basic adaptation of the cephalic socket: surgery to change the orientation of the acetabulum; e.g., Salter osteotomy, triple osteotomy, periacetabular osteotomy (PAO, Ganz), rotational acetabular osteotomy (RAO), etc.
Non-spherical adaptation of the head socket: acetabular enlargement (extension) (Staheli procedure), internal pelvic displacement osteotomy.
Proximal femoral deformity predominant: proximal femoral osteotomy (inversion, de-rotation).
Or combined surgery.
Postoperative braking or weight-free joint mobility training, as appropriate, until the osteotomy heals and ambulation resumes. Continue observation until bone maturity.