Liner malseating is rare with two modular dual-mobility designs

AIMS

The aim of this study was to evaluate the incidence of liner malseating in two commonly used dual-mobility (DM) designs. Secondary aims included determining the risk of dislocation, survival, and clinical outcomes.

METHODS

We retrospectively identified 256 primary total hip arthroplasties (THAs) that included a DM component (144 Stryker MDM and 112 Zimmer-Biomet G7) in 233 patients, performed between January 2012 and December 2019. Postoperative radiographs were reviewed independently for malseating of the liner by five reviewers. The mean age of the patients at the time of THA was 66 years (18 to 93), 166 (65%) were female, and the mean BMI was 30 kg/m² (17 to 57). The mean follow-up was 3.5 years (2.0 to 9.2).

RESULTS

Three liners (1.2%) were malseated, including two MDMs (1.4%) and one G7 (0.9%). No clinical consequence was identified from malseating. The five-year survival free of dislocation was 97.1%, including two DM and one intraprosthetic dislocation. The five-year survival free of revision was 95.4%, with seven revisions. The mean Harris Hip Scores increased from 46 (24 to 69) preoperatively to 81 (40 to 100) at two years postoperatively (p < 0.001).

CONCLUSION

The incidence of DM liner malseating after primary THA was low, with no known clinical consequences at mid-term follow-up. Malseating is not exclusive of design, and these findings emphasize the importance of careful evaluation of the liner after impaction to avoid this complication. Cite this article: Bone Joint J 2022;104-B(5):598-603.

The Impact of Surgical Technique on Patient Reported Outcome Measures and Early Complications After Total Hip Arthroplasty

BACKGROUND

This study examines patient and surgeon reported outcome measures, complications during index admission, length of stay (LOS), and discharge disposition in a series of total hip replacements (THR) performed via the direct anterior (DA) or posterolateral (PL) approach.

METHODS

Five surgeons performed 2698 total hip replacements (1457 DA vs 1241 PL) between January 2010 and June 2015. Complications during index admission were recorded using billing and claims data. Harris Hip Scores (HHS) and Hip disability and Osteoarthritis Outcome Scores (HOOS) were collected in a subset of patients.

RESULTS

Patients in the DA group had shorter LOS (2.3 DA vs 2.7 PL days, P < .001) and a larger proportion of patient discharges to home (79.0% DA vs 68.7% PL, P < .001). Surgical (0.75% DA vs 0.73% PL, P = .961) and medical (8.4% DA vs 8.1% PL, P = .766) complications during index admission were equivalent between groups. HHS (n = 462) favored the DA group at an early follow-up (P < .001), but did not differ at 1 year (P = .478). Logistic regression revealed that patients in the DA group were more likely to report no pain, no limp, walk unlimited distances, and climb stairs without the use of the railing at 3- to 6-month follow-up (P < .001). HOOSs were equivalent at all follow-ups regardless of approach.

CONCLUSION

Patients in the DA group had shorter LOS and were more likely to be discharged home. The DA group had better HHS at 3- to 6-month follow-up than patients in the PL group, with no difference in medical or surgical complications during index admission.