Pseudoacetabulum a subtle radiological feature of a chronic dislocated total hip replacement

Abnormal Anatomical and Radiological Changes in a Rare Presentation of Adult Developmental Dysplasia of the Hip

Adult presentation of bilateral dysplasia and dislocation is an extremely rare presentation. The management of adult hip dysplasia is to preserve the hip and reduce pain through surgical intervention. Hence, early diagnosis provides more options as the treatment dilemma with the late presentation is very complicated with debatable prognosis. The case presented is a 53-year old woman who complained of persistent pain in the hip region. On radiology, dysplasia and dislocation of both the hip joints were observed along with soft tissue abnormalities around the joint. In this case report, we discuss the underlying pathophysiology that might have led to the abnormal radiological and anatomical changes in the hip region and the possible treatment options in a conservatively managed case of developmental dysplasia of the hip (DDH).

Total hip arthroplasty to address chronic hip luxation with pseudoacetabulum formation in seven dogs

OBJECTIVE

To compare the outcome of dogs treated with total hip arthroplasty (THA) for chronic hip luxation and pseudoacetabulum formation to that of dogs with simple hip dysplasia and secondary osteoarthritis.

STUDY DESIGN

Retrospective, case-controlled study.

ANIMALS

Seven dogs with pseudoacetabulum (group 1) and 21 matched control dogs (group 2).

METHODS

Each dog in group 1 was matched with three control dogs, primarily according to similarity of THA implant type and size. Patterns of radiographic pathology were characterized in each dog. Outcome measures included operative time, acetabular cup position/orientation (inclination angle, angle of lateral opening, version angle) complications, and long-term outcomes. Outcome measures were compared between groups using linear regression (P = .05).

RESULTS

The presence of a pseudoacetabulum was associated with ilial remodeling and heterotopic bone formation concentric to the luxated femoral head. Exposing the native acetabulum and reducing the prosthesis were surgically challenging. The mean (SD) operative time of dogs in group 1 (96 [18] minutes) was longer than that of dogs in group 2 (63 [14] minutes; P = .00002). Cup position/orientation was not different between dogs in group 1 and group 2. One intraoperative complication and two minor postoperative complications occurred in group 1 dogs. All dogs had good long-term outcomes.

CONCLUSION

Total hip arthroplasty in dogs with a pseudoacetabulum was more challenging than in control dogs. However, the procedure provided good to excellent long-term clinical outcomes in all dogs.

CLINICAL SIGNIFICANCE

Surgeons should be prepared for the specific surgical challenges associated with THA in dogs with pseudoacetabulum formation.

Case report: Painless chronic liner dissociation of a total hip arthroplasty

BACKGROUND

Dislocation or liner dissociation of a total hip prosthesis usually results in pain and discomfort. Although several reports describe chronic dislocation and its treatment, chronic liner dissociation is an unreported complication.

CASE DESCRIPTION

We report an unrecognized dissociation and displacement of the liner of a total hip prosthesis after revision THA. The patient had virtually no pain or functional restrictions. The patient's only complaint was pain on the contralateral side, associated with a leg-length discrepancy. Since the patient had no complaints relative to the liner dissociation we elected not to pursue further treatment. The contralateral pain was treated successfully with a shoe lift.

LITERATURE REVIEW

Chronic dislocation of a THA is a rare complication and we found reports of only seven cases in the literature. We found no reports of chronic liner dissociation.

CLINICAL RELEVANCE

Orthopaedic surgeons should be aware of the possibility of this rare complication. Our case and the literature suggest treatment can be nonsurgical or surgical.

Pseudo-Acetabulum due to Heterotopic Ossification in a Child with Post Traumatic Neglected Posterior Hip Dislocation

INTRODUCTION

Traumatic neglected dislocations of hip in children are rare entity. Neglected traumatic dislocations of hip in children along with heterotopic ossification are still rare. Post traumatic neglected hip dislocations are to be diagnosed as early as possible and have to be treated with precision and aggression as the outcome of treatment for the same is not predictable.

CASE REPORT

5 year female with post-traumatic neglected hip dislocation with heterotopic ossification forming a pseudoacetabulum postero-superiorly in which femur head was lodged. The girl was operated by open reduction using Moore's Posterior approach and showed good results. Here is a mention of a rare case with a good 18 months follow up with no complication.

CONCLUSIONS

Post-traumatic neglected posterior hip dislocation mostly requires open reduction and relocation of femoral head in original acetabulum with concentric reduction. Heterotopic ossification is a rare but known complication of traumatic dislocation of hip in children. Good results can be achieved in such cases and regular follow-up of patient is required post-operatively.