Revision Total Hip Arthroplasty Using the Modular Proximal Stem Modified for Asians: Medium-Term Clinical Results and Perioperative Complications

Dissociation and Subsequent Stable Malrotation of Femoral Stem Within Sleeve After Sivash-Range of Motion Total Hip Arthroplasty: A Case Report

CASE

A 78 year-old man fell 6 months after Sivash-range of motion (S-ROM) total hip arthroplasty (THA), after which he developed hip pain and external rotation deformity. Imaging showed stem malrotation in relative retroversion. Revision THA was delayed because of medical issues, occurring 1.5 years after the fall. No corrosion was observed intraoperatively at the stem-sleeve interface. His symptoms resolved after revision THA.

CONCLUSION

We present a rare complication of S-ROM THA-dissociation of the femoral stem from the proximal sleeve, with subsequent re-engagement in static malrotation. No corrosion was observed, suggesting that the stem had stably reseated within the sleeve.

A Modified Modular Stem in Primary Total Hip Arthroplasty for Developmental Dysplasia of the Hip: Average 11-year Follow-Up in Cases With Previously Reported 3-year Clinical Results

BACKGROUND

Modular stems require careful follow-up, especially after any design modification. This study investigated the mid- to long-term outcomes of total hip arthroplasty in patients with developmental dysplasia of the hip using the S-ROM-A stem, a modified S-ROM stem for Asians.

METHODS

We previously reported short-term outcomes for all 220 dysplastic hips that underwent primary total hip arthroplasty with the S-ROM-A stem. Here, we followed the clinical and radiological outcomes of 201 of the 220 hips (91%) for a mean 11.4 years postoperatively. We also performed multivariate analysis to determine whether large anteversion angle adjustment was associated with increased osteolysis.

RESULTS

The cumulative survival rate of the stem at 168 months postoperatively was 97.4%. Two hips underwent revision surgery, including 1 due to neck trunnionosis. Characteristic distal stem fracture occurred in 3 hips (1.5%). Most partial radiolucent lines observed around the sleeve early postoperatively disappeared by 7 years, postoperatively. Mild osteolysis occurred relatively frequently (20%), but a multivariate model adjusted for polyethylene type showed no significant association between the occurrence of osteolysis and anteversion adjustment of the modular stem (stem anteversion decreased ≤-20°, P = .829; stem anteversion increased ≥+20°, P = .619).

CONCLUSION

Partial radiolucent lines early postoperatively do not affect long-term outcomes. The clinical benefits of actively adjusting the stem anteversion angle outweigh the mechanical risks. Mild osteolysis, stem fracture, and trunnionosis were relatively frequent complications. Analysis with longer follow-up and more cases are necessary to clearly determine if these complications are associated with the design modification.