Patient Presentation and History
This case details the management of Developmental Dysplasia of the Hip in an eight month old female infant presenting with a late diagnosis, highlighting the challenges inherent in this demographic. Developmental Dysplasia of the Hip represents a spectrum of conditions ranging from hip instability to frank dislocation, characterized by an abnormal relationship between the femoral head and the acetabulum. The natural history, if untreated, often leads to progressive acetabular dysplasia, femoral head deformity, premature osteoarthritis, and significant functional impairment by adulthood. Early identification and intervention are paramount for optimal outcomes.
Our index patient, an eight month old female, presented to clinic with a new onset right sided limp and asymmetry of her gluteal folds, noted by her parents. She was a first born child, delivered vaginally at full term following an uncomplicated pregnancy, though a history of oligohydramnios was noted retrospectively. There was no recorded positive family history of the condition, which is typically a significant risk factor. Universal newborn hip screening, typically performed at birth by a pediatrician utilizing Ortolani and Barlow maneuvers, did not identify any concerns. No formal risk factor based ultrasound screening was performed at four to six weeks due to lack of local protocol adherence for her identified risk factors, specifically being first born and the historical notation of oligohydramnios. She had achieved age appropriate gross motor milestones for crawling and pulling to stand, with the limp becoming apparent shortly after she began cruising. She had no known comorbidities or history of trauma.
The significance of her late presentation at eight months is critical. While newborn screening aims to identify unstable hips amenable to non operative treatment, cases presenting later, beyond the optimal window for Pavlik harness use, often necessitate more invasive interventions. The presence of a limp, which can manifest as a Trendelenburg gait or shortened limb in a walking or cruising infant, or asymmetry of skin folds, are red flags for undiagnosed hip pathology. In this age group, the hip is typically already dislocated and often irreducible due to established soft tissue contractures and morphologic changes in the acetabulum and femoral head. This progression significantly impacts treatment strategy and prognosis.
The pathophysiology of late presenting dysplasia involves a complex interplay of mechanical and biological factors. As the femoral head remains dislocated dorsolaterally, the normal stimulus for acetabular development is lost. The acetabulum becomes shallow, dysplastic, and filled with fibrofatty tissue known as the pulvinar. The ligamentum teres hypertrophies and elongates, while the transverse acetabular ligament is pulled superiorly, creating a physical block to concentric reduction. Furthermore, the iliopsoas tendon becomes contracted and acts as a bowstring across the anterior joint capsule, creating an hourglass constriction that further impedes the reentry of the femoral head into the true acetabulum. The adductor musculature also undergoes significant contracture, limiting hip abduction and tethering the proximal femur in a superiorly migrated position. Understanding these anatomical adaptations is crucial for the orthopedic surgeon, as they dictate the necessary steps during surgical intervention.
Clinical Examination Findings
A thorough clinical examination was conducted with the infant cooperative but demonstrating clear signs consistent with a chronically dislocated hip.
Inspection
Visual inspection revealed several key indicators of unilateral hip dislocation. There was noticeable asymmetry of the gluteal and thigh folds on the affected right side compared to the contralateral left side. While fold asymmetry can be a normal variant in up to thirty percent of healthy infants, in the context of a limp, it is highly suspicious for proximal femoral migration. The right lower extremity appeared subtly shorter than the left. When the child was held upright and encouraged to bear weight, a positive Trendelenburg sign was observed on the right. The pelvis dropped to the unsupported left side during weight bearing on the affected right hip, indicating profound abductor weakness and mechanical disadvantage due to the superior migration of the greater trochanter. In the supine position, a widening of the perineum was noted, a direct consequence of the lateral displacement of the femoral head and the entire proximal femoral segment.
Palpation
Palpation of the bony landmarks revealed a higher riding greater trochanter on the right side. The trochanter was palpable superiorly and posteriorly relative to its normal anatomical position, crossing the Nelaton line, which connects the anterior superior iliac spine to the ischial tuberosity. There was no localized tenderness to palpation, no erythema, and no calor, which is expected in chronic, painless dysplasia, effectively distinguishing it from acute infectious conditions such as septic arthritis or osteomyelitis of the proximal femur. Muscle tone was normal throughout all extremities, ruling out underlying spasticity or neuromuscular disorders such as cerebral palsy, which can present with secondary hip subluxation.
Range of Motion and Provocative Testing
Evaluation of hip range of motion provided critical diagnostic information and confirmed the fixed nature of the pathology.
Ortolani and Barlow maneuvers, while primary screening tools for newborn instability, were negative in this eight month old infant. This is expected as the hip is fixed in a dislocated position due to the aforementioned soft tissue contractures and capsular constrictions. The Ortolani maneuver relies on the ability to reduce a dislocated femoral head over the posterior acetabular rim, generating a palpable clunk. By eight months, the adductor contracture and the physical barriers within the acetabulum render the hip irreducible by simple manual manipulation in the awake patient.
The most reliable clinical sign in an infant of this age is limited hip abduction in flexion. With the infant supine and the hips and knees flexed to ninety degrees, gentle abduction was attempted. The left hip abducted to a normal eighty degrees, while the right hip demonstrated a firm endpoint at approximately thirty five degrees. This profound limitation is secondary to the contracture of the adductor longus and adductor brevis muscles, which adaptively shorten as the proximal femur migrates superiorly.
The Galeazzi sign, also known as the Allis sign, was unequivocally positive. With the infant supine, hips flexed to forty five degrees, knees flexed to ninety degrees, and feet planted flat on the examination table, the right knee was visibly lower than the left. This apparent femoral shortening is a classic indicator of unilateral posterior and superior hip dislocation.
The Klisic test was also performed to further corroborate the altered anatomy. The index finger was placed on the anterior superior iliac spine and the middle finger on the greater trochanter. An imaginary line connecting these two points was projected toward the umbilicus. On the normal left side, the line pointed to or above the umbilicus. On the affected right side, due to the superior migration of the greater trochanter, the line projected well below the umbilicus, confirming the proximal displacement of the femur.
Neurological and Vascular Assessment
A comprehensive neurological and vascular examination of the lower extremities is a mandatory prerequisite before any intervention. The infant demonstrated spontaneous, symmetric movement of the distal extremities. Patellar and Achilles reflexes were symmetric and normoactive. There was no evidence of clonus or Babinski sign. Sensation to light touch, assessed by withdrawal to gentle stimulation, appeared intact across all dermatomes. Dorsalis pedis and posterior tibial pulses were palpable and symmetric, with brisk capillary refill in the toes. Documenting a normal baseline neurovascular status is critical, as subsequent closed or open reduction techniques, particularly those requiring significant abduction or manipulation, carry a known risk of iatrogenic injury to the femoral nerve, sciatic nerve, or the medial circumflex femoral artery.
Imaging and Diagnostics
The diagnostic workup for a late presenting infant relies heavily on radiographic evaluation, as the cartilaginous anlage of the femoral head and acetabulum have begun to ossify, making plain radiography the gold standard at this age.
Plain Radiographic Evaluation
An anteroposterior radiograph of the pelvis and a frog leg lateral view were obtained. Proper positioning is critical; the pelvis must be neutral, without tilt or rotation, to ensure accurate measurement of the radiographic indices. Rotation can be assessed by evaluating the symmetry of the obturator foramina and the iliac wings.
The anteroposterior pelvic radiograph revealed classic findings of a chronic, high dislocation. Hilgenreiner line, a horizontal line drawn through the triradiate cartilages, and Perkin line, a vertical line drawn perpendicular to Hilgenreiner line through the lateral edge of the ossified acetabular roof, were utilized to divide the hip into four quadrants, known as the Ombredanne quadrants. In a normal hip, the ossific nucleus of the femoral head or the medial beak of the femoral metaphysis should reside in the inferomedial quadrant. In our index patient, the right proximal femoral metaphysis was located in the superolateral quadrant, confirming a complete dislocation.
The ossific nucleus of the right capital femoral epiphysis was absent, whereas the left ossific nucleus was present and well formed. This delay in ossification is a hallmark of developmental dysplasia, resulting from the lack of normal mechanical loading and altered vascularity in the dislocated position.
Shenton line, a continuous radiographic arc formed by the medial border of the femoral neck and the superior border of the obturator foramen, was broken on the right side. The femoral portion of the line was displaced superiorly relative to the pelvic portion, further quantifying the degree of proximal migration.
The acetabular index, defined as the angle formed by Hilgenreiner line and a line drawn along the ossified acetabular roof, was measured to assess the degree of dysplasia. The normal acetabular index at eight months of age is typically less than twenty five degrees. In this patient, the left acetabular index was twenty two degrees, while the right acetabular index was significantly elevated at thirty eight degrees, indicating severe secondary acetabular dysplasia. The acetabular roof appeared sclerotic and upsloping, lacking the normal concavity required to contain the femoral head.
Ultrasonography Limitations
While dynamic ultrasonography, utilizing the Graf classification or Harcke dynamic method, is the modality of choice for infants under six months of age, its utility diminishes significantly once the capital femoral epiphysis begins to ossify. The ossific nucleus creates an acoustic shadow that obscures the deeper structures of the acetabulum, including the triradiate cartilage and the lower ilium, making accurate measurement of the alpha and beta angles unreliable. Therefore, ultrasound was not utilized in the diagnostic workup for this eight month old patient.
Advanced Imaging Indications
Magnetic Resonance Imaging and computed tomography are not typically required for the initial diagnosis of developmental dysplasia in an infant. However, they play a critical role in the postoperative phase. Following closed or open reduction and spica cast application, a limited sequence Magnetic Resonance Imaging without contrast or a low dose computed tomography scan is the standard of care to confirm concentric reduction. Magnetic Resonance Imaging is preferred due to the absence of ionizing radiation and its superior ability to visualize the cartilaginous femoral head, the labrum, and any residual soft tissue interposition such as an inverted limbus or hypertrophied pulvinar.
Intraoperative arthrography is an indispensable diagnostic and interventional tool. It involves the injection of radiopaque contrast dye directly into the hip joint capsule under fluoroscopic guidance. The arthrogram provides a real time, dynamic outline of the cartilaginous surfaces and the intraarticular soft tissues. It is essential for identifying the specific anatomical blocks to reduction, such as the hourglass constriction of the capsule caused by the iliopsoas tendon, the presence of a medial dye pool indicating incomplete seating of the femoral head, or the rose thorn sign indicative of an inverted labrum.
Differential Diagnosis
The presentation of a painless limp, leg length discrepancy, and limited hip abduction in an infant requires a systematic evaluation of several potential etiologies. While developmental dysplasia is the most likely diagnosis given the clinical and radiographic findings, other conditions must be considered and systematically ruled out.
| Condition | Key Clinical Findings | Radiographic Hallmarks | Pathophysiology |
|---|---|---|---|
| Developmental Dysplasia of the Hip | Painless limp, limited abduction, positive Galeazzi sign, asymmetric skin folds. | Superolateral displacement of proximal femur, elevated acetabular index, broken Shenton line, delayed ossification of epiphysis. | Abnormal relationship between femoral head and acetabulum leading to secondary capsular and bony changes. |
| Septic Arthritis Sequelae | History of acute febrile illness, severe pain with micromotion, subsequent limp and shortening. | Destruction of the capital femoral epiphysis, joint space narrowing, potential pathological dislocation, severe metaphyseal changes. | Bacterial infection of the joint space causing rapid chondrolysis, capsular distension, and subsequent joint destruction. |
| Infantile Coxa Vara | Painless limp, Trendelenburg gait, prominent greater trochanter, limited abduction and internal rotation. | Decreased neck shaft angle (less than 120 degrees), vertical physis, inverted Y fragment in the inferior femoral neck. | Primary ossification defect in the medial aspect of the proximal femoral physis leading to progressive varus deformity. |
| Proximal Femoral Focal Deficiency | Severe leg length discrepancy noted at birth, bulky proximal thigh, flexed and abducted hip posture. | Absence or severe hypoplasia of the proximal femur, variable acetabular dysplasia, frequent absence of the fibula. | Embryological defect in the formation of the proximal cartilaginous anlage of the femur. |
| Neuromuscular Hip Subluxation | Spasticity, hyperreflexia, delayed motor milestones, scissoring gait. | Coxa valga, persistent femoral anteversion, progressive superolateral subluxation over time. | Imbalance of muscle forces across the hip joint, typically excessive adductor and flexor tone, leading to gradual displacement. |
In this index case, the absence of an acute febrile illness or severe pain ruled out septic arthritis. The normal neck shaft angle and absence of a vertical physis ruled out infantile coxa vara. The normal distal extremity anatomy and relatively mild leg length discrepancy ruled out proximal femoral focal deficiency. Finally, the normal neurological examination and absence of spasticity eliminated neuromuscular etiologies.
Surgical Decision Making and Classification
The management of developmental dysplasia in the late presenting infant requires a nuanced approach, balancing the need for a concentric, stable reduction against the risk of iatrogenic complications, most notably avascular necrosis of the femoral head.
Classification Systems
The severity of the dislocation is typically classified using the Tonnis classification system, which is based on the position of the ossific nucleus or the proximal femoral metaphysis relative to the Perkin line and Hilgenreiner line on an anteroposterior radiograph.
* Grade I: The ossific nucleus is medial to the Perkin line and inferior to the Hilgenreiner line (normal or mild subluxation).
* Grade II: The ossific nucleus is lateral to the Perkin line but inferior to the Hilgenreiner line.
* Grade III: The ossific nucleus is lateral to the Perkin line and at the level of the Hilgenreiner line.
* Grade IV: The ossific nucleus is lateral to the Perkin line and superior to the Hilgenreiner line.
Our index patient demonstrated a Tonnis Grade IV dislocation, indicating a high, complete dislocation with significant proximal migration.
The International Hip Dysplasia Institute classification is another valuable tool, particularly when the ossific nucleus is absent. It utilizes the H line (Hilgenreiner line) and a P line (perpendicular to the H line at the lateral margin of the acetabulum) to create quadrants. The classification is based on the position of the midpoint of the proximal femoral metaphysis. This patient would be classified as an International Hip Dysplasia Institute Grade IV, as the metaphyseal midpoint was located superolateral to the acetabular margin.
Operative Versus Non Operative Management
The optimal treatment window for non operative management utilizing a Pavlik harness is typically limited to infants under six months of age. Beyond this age, the failure rate of the Pavlik harness increases dramatically due to the physical size and strength of the infant, the establishment of rigid soft tissue contractures, and the secondary morphologic changes in the joint. Attempting harness treatment in an eight month old with a Tonnis Grade IV dislocation is generally contraindicated, as it prolongs the time to definitive reduction and carries a high risk of failure and potential harm, including "Pavlik harness disease" or inferior dislocation.
Therefore, the decision algorithm for an eight month old patient dictates an examination under anesthesia, arthrography, and an attempt at closed reduction. If closed reduction is successful, stable, and achievable within a safe zone of positioning, a spica cast is applied. However, if the reduction requires excessive force, if the hip is unstable within the safe zone, or if the arthrogram demonstrates significant soft tissue interposition preventing a concentric reduction, an immediate open reduction is indicated.
The concept of the Ramsey safe zone is paramount during closed reduction. It represents the arc of motion between the angle of maximal abduction and the angle of redislocation in adduction. A safe zone of at least twenty to thirty degrees is generally required for successful closed management. If the hip requires greater than sixty degrees of abduction to maintain reduction, the risk of avascular necrosis increases exponentially due to compression of the medial circumflex femoral artery against the cartilaginous acetabular margin. In such cases, surgical release of the adductor contracture or proceeding to open reduction is necessary to relieve the vascular compression.
Given the clinical presentation of a rigid adductor contracture and a high dislocation, the preoperative plan for this patient included an examination under anesthesia, percutaneous adductor tenotomy, arthrogram, and an anticipated open reduction via an anterior approach, as closed reduction was highly likely to fail or result in an unacceptable degree of tension on the proximal femur.
Surgical Technique and Intervention
The patient was taken to the operating room and placed under general endotracheal anesthesia. Prophylactic intravenous antibiotics were administered prior to incision.
Examination Under Anesthesia and Arthrography
The patient was positioned supine on a radiolucent table. An examination under anesthesia confirmed the preoperative findings of limited abduction and a positive Galeazzi sign. A percutaneous adductor longus tenotomy was performed to release the primary deforming force limiting abduction. A small stab incision was made near the origin of the adductor longus at the pubis, and the tendon was released using a scalpel, taking care to avoid the anterior branch of the obturator nerve. Following the tenotomy, abduction improved significantly but a palpable clunk of reduction could not be elicited.
An intraoperative arthrogram was then performed. An eighteen gauge spinal needle was introduced into the hip joint via an anterior approach, just lateral to the femoral neurovascular bundle. The position was confirmed fluoroscopically, and radiopaque contrast material was injected. The arthrogram revealed a severe hourglass constriction of the capsule, a large medial dye pool indicating a hypertrophied pulvinar, and a blunted, inverted labrum. Attempted closed reduction under fluoroscopy demonstrated that the femoral head could be brought down to the level of the acetabulum, but it would not seat concentrically due to the soft tissue interposition. The medial dye pool remained greater than five millimeters, which is an unacceptable parameter for closed treatment. The decision was made to proceed immediately to an open reduction.
Anterior Approach to the Hip
An open reduction via an anterior approach was selected, as it provides excellent visualization of the intraarticular obstacles to reduction and allows for a robust capsulorrhaphy. A bikini incision, a cosmetic variation of the classic Smith Petersen approach, was utilized. The incision was made obliquely within the Langer lines of the groin crease, starting just inferior to the anterior superior iliac spine and extending medially.
The subcutaneous tissue was sharply divided. The superficial fascia was incised, and the lateral femoral cutaneous nerve was carefully identified and retracted medially to prevent iatrogenic neuropraxia or neuroma formation. The superficial internervous plane between the sartorius muscle, innervated by the femoral nerve, and the tensor fasciae latae, innervated by the superior gluteal nerve, was developed.
The dissection was carried deeper to expose the plane between the rectus femoris, innervated by the femoral nerve, and the gluteus medius, innervated by the superior gluteal nerve. The ascending branch of the lateral circumflex femoral artery, which crosses this interval, was identified, ligated, and divided to allow for adequate exposure and to prevent postoperative hematoma.
The direct head of the rectus femoris was detached from its origin on the anterior inferior iliac spine and reflected distally. The reflected head of the rectus femoris was also released from the superior acetabular rim. This provided clear visualization of the anterior hip capsule.
Clearing the Obstacles to Reduction
The anterior capsule was meticulously cleared of overlying soft tissue. The iliopsoas tendon, which courses over the anterior capsule and creates the hourglass constriction, was identified. The tendon was isolated and released at the level of the pelvic brim, allowing the muscle belly to retract proximally. This fractional lengthening relieves the deforming force on the capsule and removes a major impediment to reduction.
An arthrotomy was performed. A T shaped capsulotomy is typically preferred. An incision was made parallel to the acetabular rim, followed by a perpendicular incision extending distally along the anterior femoral neck. The capsular flaps were tagged with heavy non absorbable sutures for later repair.
Upon opening the capsule, the intraarticular pathology was evident. The ligamentum teres was markedly hypertrophied and elongated. It was excised using electrocautery and sharp dissection, taking care not to damage the underlying articular cartilage of the femoral head.
The true acetabulum was inspected. It was filled with a dense, fibrofatty pulvinar. This tissue was meticulously removed using a curette and pituitary rongeurs until the medial wall of the acetabulum, the cotyloid fossa, was clearly visualized.
The transverse acetabular ligament, which spans the inferior acetabular notch, was identified. In chronic dysplasia, this ligament is often pulled superiorly and anteriorly, acting as a sling that prevents the femoral head from seating inferiorly. The transverse acetabular ligament was radially incised to open the inferior aspect of the acetabulum.
Finally, the labrum was inspected. It was blunted and partially inverted. Using a blunt probe, the labrum was gently everted. Care must be taken not to excise the labrum, as it is critical for future acetabular development and joint stability.
Reduction and Capsulorrhaphy
With all obstacles cleared, the femoral head was gently manipulated into the acetabulum. The reduction was concentric and stable. The hip was taken through a range of motion to assess stability. The hip was found to be most stable in approximately ninety degrees of flexion, forty degrees of abduction, and neutral rotation.
A robust capsulorrhaphy is essential to maintain the reduction and eliminate the redundant capsular volume. The inferior capsular flap was advanced superiorly and laterally, and sutured to the superior capsular margin and the periosteum of the ilium. The superior flap was then brought distally and medially, overlapping the inferior flap in a vest over pants fashion. This capsular shift tightening effectively stabilizes the joint and prevents superior migration of the femoral head.
The rectus femoris was reattached to the anterior inferior iliac spine. The wound was irrigated copiously. The fascia, subcutaneous tissue, and skin were closed in layers using absorbable sutures. A sterile dressing was applied.
Spica Cast Immobilization
While still under anesthesia, the infant was placed on a spica table. A one and a half hip spica cast was applied. The cast incorporated the entire affected right lower extremity down to the toes, the pelvis, and the contralateral left lower extremity down to just above the knee.
The positioning within the cast is critical. The hip was immobilized in the "human position," consisting of ninety to one hundred degrees of flexion, forty to fifty degrees of abduction, and neutral rotation. Excessive abduction, the "frog leg" position, must be strictly avoided to minimize the risk of avascular necrosis. The cast was carefully molded over the greater trochanters and the iliac crests to ensure stability. Adequate padding was placed over all bony prominences, and a generous perineal opening was created to allow for hygiene.
Post Operative Protocol and Rehabilitation
The postoperative management following open reduction of developmental dysplasia is a prolonged and meticulous process, requiring close collaboration between the orthopedic surgeon, the nursing staff, and the parents.
Immediate Post Operative Care and Imaging
Immediately following cast application and recovery from anesthesia, the patient underwent a limited sequence Magnetic Resonance Imaging scan. This is the gold standard to confirm concentric reduction of the cartilaginous femoral head within the acetabulum while the patient is immobilized in the spica cast. The Magnetic Resonance Imaging confirmed that the femoral head was deeply seated within the true acetabulum, with no evidence of posterior subluxation or soft tissue interposition.
The patient was admitted to the pediatric ward for twenty four to forty eight hours for pain management, observation of neurovascular status, and education of the parents regarding spica cast care. The parents were instructed on techniques for diapering within the cast, positioning to prevent pressure sores, and monitoring for signs of compartment syndrome or skin breakdown.
Cast Management and Duration
The total duration of spica cast immobilization for an open reduction is typically twelve weeks. The initial cast is left in place for six weeks. At the six week mark, the patient returns to the operating room for a cast change under general anesthesia. This allows for a thorough inspection of the skin, assessment of clinical stability, and application of a new, well fitting cast as the child's swelling has subsided and growth has occurred. An anteroposterior radiograph of the pelvis is obtained out of the cast to assess the maintenance of reduction and the early signs of acetabular remodeling.
Following the second six week period in the spica cast, the cast is removed entirely in the clinic setting. Radiographs are repeated. At this stage, the hip is typically clinically stable, but the acetabulum remains dysplastic and requires continued mechanical stimulation for proper development.
Orthotic Management and Long Term Surveillance
Upon removal of the spica cast, the patient is transitioned to a rigid abduction orthosis, such as a Rhino cruiser or an Ilfeld splint. The orthosis maintains the hips in flexion and abduction, continuing to direct the femoral head into the acetabulum to stimulate remodeling. The orthosis is worn full time, twenty three hours a day, for an additional six to twelve weeks, followed by a gradual weaning protocol to nighttime and naptime wear. The duration of orthotic management is dictated by the progressive improvement of the acetabular index on serial radiographs.
Long term surveillance is mandatory and continues until skeletal maturity. The child is evaluated clinically and radiographically every six months initially, and then annually. The primary goals of long term follow up are to monitor for the development of avascular necrosis and to assess the resolution of acetabular dysplasia.
If the acetabular index fails to normalize over time, or if there is evidence of persistent lateral subluxation or a failure of the center edge angle of Wiberg to improve, a secondary
