Developmental Dysplasia

Developmental dysplasia of the hip (DDH) is not a cause of hip pain. It is simply a morphologic condition that makes the hip vulnerable to an intraarticu-lar lesion that may then become symptomatic. The three most likely structures to be involved are the ac-etabular labrum, articular surface, and ligamentum teres.

Accompanying a shallow bony acetabulum, the labrum may be enlarged, assuming a more important role as a weight-bearing surface as well as added responsibility for joint stability. This hypertrophic labrum is thus exposed to greater joint reaction forces and may be at increased risk for developing symptomatic tearing.1-3 Inversion of the acetabular labrum is also known to occur in association with dysplasia, being entrapped within the joint and again being a source of painful tearing.4,5

The reduced area of the acetabular articular surface results in increased contact forces,6,7 which can result in early development of degenerative wear and may make the articular cartilage more vulnerable to acute fragmentation.8-11

Third, elongation or hypertrophy of the ligamen-tum teres accompanies lateral subluxation of the femoral head within the acetabulum.12,13 Entrapment of this ligament can be a source of significant me chanical hip pain, whether from its redundant nature or partial degenerate rupture.

Thus, dysplasia is well recognized as an etiologic factor in the development of various painful in-traarticular lesions that may be amenable to arthro-scopic intervention. In fact, in our study, which is the only published report on outcomes of arthros-copy in a dysplastic population, the results were comparable with those previously published in a general population.14 However, several caveats need to be fully appreciated.

It is important to assess patients carefully for the presence of dysplastic disease of the hip. Although ar-throscopic debridement may result in significant symptomatic improvement, it may not seriously influence the long-term outlook. Especially for young individuals, arthroscopy should not be used solely for symptomatic improvement when long-term issues need to be addressed. Specifically, patients who are candidates for osteotomy to improve the joint mechanics and weight distribution must be carefully assessed.

As noted, the enlarged labrum accompanying a shallow acetabulum may carry greater weight-bearing responsibility as well as provide a buttress to supero-lateral subluxation of the femoral head. It is unlikely that simple debridement of the deteriorated portion of the labrum will accentuate this subluxation potential, but great care must be taken in the debridement procedure, especially avoiding an overly zealous resection.

Similarly, indiscriminate debridement of the lig-amentum teres should be avoided. The vessel of the ligamentum teres remains patent and contributes to the blood supply of the femoral head in a significant percentage of adults. Arbitrary debridement could unnecessarily place the femoral head at risk for avascular necrosis. However, it seems unlikely that debridement of the ruptured portion should present a problem, and it has produced gratifying symptomatic results.

In summary, radiographic evidence of dysplasia is not a contraindication to arthroscopy, nor is it necessarily an indicator of poor outcome. Results are more dictated by the nature of the pathology. Nonetheless, it is prudent to view arthroscopy as but one tool in the complement of resources necessary in the assessment and management of patients with developmental dysplasia of the hip.

Case 1

A 14-year-old girl was referred with a 4-month history of painful locking and catching of her right hip. Symptoms first occurred when simply raising her leg to step over a railing. Her symptoms had since been unremitting. Her history was remarkable for dysplastic disease of both hips since birth. These were initially treated with closed reduction, but she had subsequently undergone multiple osteotomies of the proximal femur and pelvis. Most recently, she was being evaluated for an acetabular procedure to improve the coverage of her femoral head when she developed incapacitating mechanical right hip symptoms. Radiographs revealed changes consistent with her underlying disease and previous surgical procedures as well as slight lateral joint space loss on the right compared with the left (Figure 15.1A).

Based on her symptoms and examination findings, arthroscopy was recommended as a method to assess the extent of intraarticular damage that may be contributing to her symptoms and to see if this could be addressed. She was found to have an unstable inverted labrum (see Figure 15.1B). This was debrided in a cautious fashion (see Figure 15.1C). Care was taken to excise the entrapped portion contributing to her symptoms while preserving as much of the remaining labrum as possible to avoid potentially destabilizing the joint. Additionally, there was grade IV articular loss of the acetabulum. The unstable fragments were debrided, creating a stable edge of surrounding cartilage (see Figure 15.1D). Microfracture of the lesion was performed to stimulate a fibrocartilaginous healing response (see Figure 15.1E). Occluding the inflow confirmed vascular access through the perforations (see Figure 15.1F). Postoperatively, she was maintained on a strict protected weight-bearing status for 2 months, emphasizing range of motion. She was then able to resume normal light daily activities with resolution of her mechanical hip pain.

Case 2

A 16-year-old boy presented with a 9-month history of pain and locking of his left hip. This first occurred while playing football as a freshman in high school. He had received no previous specific treatment, but was known to have a developmental abnormality of his hip since early childhood. Radiographs revealed evidence of a separate bone fragment within the femoral head (Figure 15.2A), which was further substantiated by a computed tomography (CT) scan (Figure 15.2B).

With his mechanical symptoms and imaging evidence of a loose fragment, arthroscopy was recommended. The fragment was actually found to be fixed within the femoral head, but there was a grade IV unstable articular fragment over this area that was debrided (see Figure 15.2C-E). Postopera-tively, he had resolution of his mechanical pain and catching.

Case 3

A 37-year-old woman presented with a 4-year history of progressively worsening right hip pain. There was no history of injury or precipitating event; she simply began experiencing discomfort that had worsened over recent months. Twisting maneuvers were especially painful. Her examination findings suggested that her hip joint was the source of pain. Radiographs revealed evidence of modest underlying dysplasia but were otherwise unremarkable (Figure 15.3A). Magnetic resonance imaging (MRI) was also unremarkable. She then underwent 6 months of continued activity restriction as well as various trials of oral antiinflammatory medications and physical therapy without improvement. She obtained pronounced temporary alleviation of her symptoms from a fluoroscopically guided intraarticu-lar injection of anesthetic.

Based on her clinical circumstances, arthroscopy was offered as the next step in her management. She was found to have a hypertrophic ligamentum teres with an accompanying degenerate rupture that was debrided (see Figure 15.3B-D). Postoperatively, she demonstrated pronounced symptomatic improvement and was able to resume fitness exercises.

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