Acetabular cup revision with the use of the medial protrusio technique at an average follow-up of 6.6 years

Complications and outcomes of total hip arthroplasty in dogs with luxoid hip dysplasia: 18 cases (2010-2022)

OBJECTIVE

To describe the complications and outcomes in dogs with luxoid hip dysplasia (LH) undergoing total hip arthroplasty (THA) and compare complication rates with THA in non-LH dogs.

STUDY DESIGN

Retrospective study.

SAMPLE POPULATION

Client-owned dogs (n = 217) undergoing primary THA (n = 238).

METHODS

Medical records (2010-2022) of dogs undergoing THA were reviewed, and LH was defined as complete dorsal displacement of the femoral head from the acetabulum on lateral projection radiographs. Major or catastrophic complications, revisions, and outcomes were recorded for all dogs and they were compared between LH and non-LH groups.

RESULTS

Eighteen cases met the subcriterion for the LH group and 220 cases met the subcriterion for inclusion in the non-LH group. There were 14 complications in 13/18 dogs with LH; seven were intraoperative (femoral fissure/fracture) and seven were postoperative (dorsal luxation, n = 5; femoral fracture, n = 1; acetabular cup septic loosening, n = 1). Revisions were performed for all LH dogs that encountered complications; satisfactory outcomes were achieved in 12/13 dogs. Overall, LH dogs had a higher risk of developing complications (p < .001), including intraoperative fracture (p < .001) and postoperative dorsal luxation (p = .019) when compared with non-LH dogs.

CONCLUSION

Luxoid hip dysplasia was associated with a higher risk of major complications following THA in dogs, specifically intraoperative fissure/fracture and postoperative dorsal luxation. Despite the increased risk, revisions typically yielded satisfactory outcomes.

CLINICAL SIGNIFICANCE

Luxoid hip dysplasia is an important risk factor for the development of major complications in dogs undergoing THA.

Acetabular Reconstruction With the Medial Protrusio Technique for Complex Primary and Revision Total Hip Arthroplasties

BACKGROUND

In the setting of acetabular deficiency during total hip arthroplasty (THA), the medial protrusio technique (MPT) allows for increased component coverage while avoiding excessive component abduction or elevation of the hip center. The technique involves controlled reaming through the medial acetabular wall while maintaining the continuity of the anterior and posterior columns. The purpose of this study is to analyze the results of the largest reported series to date of primary and revision THAs using the MPT.

METHODS

A retrospective review of THAs performed by a single surgeon from July 2004 to July 2010 identified 102 patients who underwent THA necessitating the use of the MPT (primary 86 and revision 16), with at least 2 years follow-up.

RESULTS

This study reports the largest series to date of primary and revision THAs using the MPT for acetabular deficiency. Postoperatively, mean Harris hip score was 86 (range 31-96). There was no correlation with degree of medialization and change in Harris hip score (P = .12). At mean follow-up of 41.1 months (range 24-92 months), there were no intrapelvic structure injuries and no acetabular components required revision. The MPT provided a safe and effective method for addressing acetabular deficiency and avoiding component malposition.

CONCLUSION

The MPT provided a safe and effective method for addressing acetabular deficiency in this large series of patients. The technique was successful at improving component coverage while maintaining an anatomic hip center and avoiding excessive component abduction. Fixation remained durable with no cases of loosening at final follow-up.

Do jumbo cups cause hip center elevation in revision THA? A radiographic evaluation

BACKGROUND

Acetabular revision THA with use of a large (jumbo) cup is an effective treatment for many cavitary and segmental peripheral bone defects. However, hip center elevation may occur with use of a jumbo cup owing to reaming superiorly and/or because of the increased diameter of the jumbo cup compared with the native acetabulum.

QUESTIONS/PURPOSES

In our jumbo cup revision THAs, we attempted to avoid hip center elevation by placing the inferior edge of the cup at the inferior acetabulum. In this study, we asked (1) how much of an elevation in the hip center is observed radiographically with use of jumbo cups, and (2) how effective was our technique in minimizing hip center elevation during revision THA in clinical practice?

METHODS

We retrospectively reviewed radiographic data for all patients, from one surgeon's practice, who received a jumbo cup (defined as cup size ≥ 66 mm in men, ≥ 62 mm in women) during an acetabular revision between 1998 and 2012 and who had an anatomically placed THA or no THA on the contralateral side (so as to be able to make comparisons); 98 patients were identified and included. The height of the revised hip center was measured relative to the contralateral normal hip. Cup elevation resulting from superior reaming was determined by measuring the distance from the inferior cup edge to the interteardrop line. The mean hip center elevation and cup position relative to the interteardrop line in male and female patients were compared using unpaired t-tests.

RESULTS

Radiographic analysis showed a mean hip center elevation of 11 mm. On average, 1 mm of the measured hip center elevation was the result of cup placement superior to its planned position at the interteardop line.

CONCLUSIONS

Our results indicate that revision THA with a jumbo cup is associated with hip center elevation despite placement of the cup at the inferior acetabulum. An increase in femoral head length may be needed to compensate for hip center elevation with use of a jumbo cup.

LEVEL OF EVIDENCE

Level III, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence.

Do jumbo cups cause hip center elevation in revision THA? A computer simulation

BACKGROUND

Acetabular revision THA with use of a large (jumbo) cup is an effective treatment for many cavitary and segmental peripheral bone defects. However, the jumbo cup may result in elevation of the hip center and protrusion through the anterior acetabular wall as a result of the oversized geometry of the jumbo cup compared with the physiologic acetabulum.

QUESTIONS/PURPOSES

The purpose of this computer simulation was to determine how much elevation of the hip center and anterior wall protrusion occurs in revision THA with use of a jumbo cup technique in which the inferior edge of the jumbo cup is placed at the inferior acetabular rim and the superior edge of the jumbo cup is placed against host bone at the superior margin of a posterosuperior bone defect.

METHODS

Two hundred sixty-five pelvic CT scans were analyzed by custom CT analytical software. The computer simulated oversized reaming. The vertical and anterior reamer center shifts were measured, and anterior column bone removal was determined.

RESULTS

The computer simulation demonstrated that the hip center shifted 0.27 mm superiorly and 0.02 mm anteriorly, and anterior column bone removal increased 0.86 mm for every 1-mm increase in reamer diameter.

CONCLUSIONS

Our results indicate that the jumbo cup technique results in hip center elevation despite placement of the cup adjacent to the inferior acetabulum. For a hypothetical increase from a 54-mm socket to a 72-mm socket, as one might see in the context of the revision of a failed THA, our model would predict an elevation of the hip center of approximately 5 mm and loss of approximately 15 mm of anterior column bone. This suggests that an increase in femoral head length may be needed to compensate for the hip center elevation caused by the use of a large jumbo cup in revision THA. A jumbo cup may also result in protrusion through the anterior wall.