Hip-spine relationship in total hip arthroplasty - Simplifying the concepts

Increased Cup Anteversion May Not Prevent Posterior Dislocation in Patients With Abnormal Spinopelvic Characteristics in Total Hip Arthroplasty

Background

The aims of this study were to (1) assess the degree of variation in acetabular component placement and combined anteversion in a large cohort of dislocating total hip arthroplasties; (2) assess the spinopelvic characteristics of the cohort; and (3) examine the association between cup anteversion and reported direction of instability.

Methods

A commercial database of 245 dislocating total hip arthroplasties referred for postoperative computed tomography and functional radiographic imaging and analysis were reviewed. Spinopelvic parameters and cup and stem positions were measured in the supine, standing, flex-seated, and anterior pelvic plane (APP) positions. Spinopelvic characteristics were stratified by high, neutral, and low cup anteversion using thresholds of >35° and <15° anteversion in standing, respectively.

Results

In the dislocation cohort, 62%, 45%, and 42% of cups were within the safe zone in supine, standing, and the APP, respectively (P < .001). Patients with high vs neutral or low cup anteversion had significantly stiffer spines, more posterior pelvic tilt in standing, greater changes in pelvic tilt, and higher sagittal imbalance. Of the 45 patients with high cup anteversion and reported instability direction, 60% and 40% were reported to have posterior and anterior instability, respectively, with no differences in spinopelvic characteristics.

Conclusions

In this dislocating cohort, there is a decreased percentage of cups within the safe zone in the APP and standing position compared to the supine reference. In addition, we found that patients having poor spinopelvic characteristics and high cup anteversion can still dislocate, suggesting that adjusting cup anteversion alone may not be sufficient for preventing instability.

The short-term outcomes of cementless stem for hip arthroplasty in the elderly patients: comparison with patients < 65 years

OBJECTIVE

The use of cement or cementless femoral stem prosthesis for hip arthroplasty in elderly patients has been controversial. This study investigated the efficacy and safety of cementless femoral stem in elderly patients (age ≥ 65 years).

METHODS

The short-term efficacy of primary hip arthroplasty with cementless femoral stem in our hospital from January 2014 to June 2021 was retrospectively analyzed. Patients were divided into two groups according to age: young group (< 65 years) and the elder group (≥ 65 years). The evaluation index was the Harris Hip score (Harris), postoperative femoral stem prosthesis sinking distance and femoral plant-related complications (periprosthetic fracture, prosthesis loosening, infection, dislocation, etc.).

RESULTS

There were 72 cases of 86 hips in the young group and 83 cases of 92 hips in the elder group. The recovery trend of functional score in the elder group was similar to that in the young group, and the Harris score increased from (38.35 ± 18.21) before surgery to (86.91 ± 12.55) at last follow-up (p < 0.01). Compared with the two groups at the same time of 3 months, 6 months and 12 months after operation, the sinking distance of the elder group was significantly greater (P < 0.05). Even in the elder group, there was a significant difference in sinking distance between 6 and 3 months after surgery (2.44 ± 0.49 mm vs 2.10 ± 0.65 mm, P = 0.004). However, there was no significant difference between 12 and 6 months (2.53 ± 0.53 mm vs 2.44 ± 0.49 mm, P = 0.40). A total of 10 patients in the elder group and 6 patients in the young group had a complication event (P = 0.36).

CONCLUSIONS

Elderly patients with cementless femoral stems can achieve metal-bone integration slightly longer than young patients, but short-term clinical outcomes can be restored to a satisfactory level with adequate safety. However, the long-term efficacy still needs to be verified by multicenter, large sample size and prospective clinical follow-up results.

The incidence of hip dislocation after posterior approach primary total hip arthroplasty: comparison of two different posterior repair techniques

INTRODUCTION

Total hip arthroplasty (THA) remains one of the most successful orthopedic surgical procedures. The posterior approach is associated with a higher incidence of post-operative dislocations than others. Adequate posterior soft tissue repair techniques, including capsulorrhaphy and transosseous bone sutures in the greater trochanter effectively reduce the dislocation rate. Post-operative "posterior hip precautions" were historically believed to reduce dislocation risks, although not clearly proven. The first protocol consists of capsulorrhaphy with the prescription of post-operative posterior hip precautions (TT) and the second, transosseous bone sutures without precautions (TB). This study aims to determine the optimal protocol to decrease the dislocation rate following posterior approach primary THA.

MATERIALS AND METHODS

A 10-year retrospective case-control chart review analyzed demographic, pre-, intra-, and post-surgical parameters. Primary outcomes were the difference in dislocation and revision surgery rates between protocols. Secondary outcomes included the incidence of recurrent dislocations and the identification of predictors of dislocation.

RESULTS

2,242 THAs were reviewed and 26 (1.2%) resulted in dislocation. Increased age (p = 0.04) ASA score (p = 0.03) and larger acetabular cup size (p < 0.001) were associated with heightened risk. Tendon to tendon (TT) repair saw a 1.62% dislocation rate versus 0.98% for tendon-to-bone (TB) repair, although statistically insignificant (p = 0.2). Transosseous repair resulted in recurrent dislocations for 8/16 (50%) patients compared to 6/10 (60%) in the suture group (p ≤ 0.001). No significance was found for prescription of posterior hip precautions.

CONCLUSIONS

To our knowledge, this is the first study to perform a direct comparison of TT repair with posterior precautions to TB repair without posterior precautions. Similarity in dislocation rate, decreased recurrent events and the alleviated patient burden from precautions leads the authors to recommend the TB repair without precautions for a successful THA.