Transient subluxation of the femoral head after total hip replacement

Periprosthetic fracture following anterior approach or dislocation after posterior approach: which one is the lesser evil?

INTRODUCTION

The most common approaches in total hip arthroplasty (THA) have different complication profiles; anterior-approach (AA-THA) has an increased risk of periprosthetic fractures (PPF); posterior-approach (PA-THA) is associated with higher dislocation risk. However, the relative severity of one versus the other is unknown. This study aims to compare outcome of patients who suffered PPF after AA-THA with those that sustained dislocation after PA-THA.

METHODS

This is a retrospective, single-center, multi-surgeon, consecutive case-series of primary THA patients. In a cohort of 9867 patients who underwent THA, 79 fulfilled the approach-specific, post-operative complication criteria, of which 44 were PPF after AA-THA and 35 with dislocation after PA-THA (age 67.9 years (range: 38.0-88.1), 58.2% women). Outcome included complication- and revision- rates, and patient-reported outcomes including Oxford Hip Score (OHS).

RESULTS

At 5.8 years follow-up (range: 2.0-18.5), reoperation was more common in the dislocation after PA-THA group (23/35 vs. 20/44; p = 0.072). Change of surgical approach occurred in 15/20 of patients with PPF after AA-THA, but none in those with dislocation after PA-THA. Following re-operation, complication rate was greater in the PPF group (9/20 vs. 4/23; p = 0.049). At latest follow-up, OHS were superior in the PPF after AA-THA group [42.6 (range: 25.0-48.0) vs. 36.6 (range: 21.0-47.0); p = 0.006].

CONCLUSION

Dislocation following PA-THA is more likely to require revision. However, PPF following AA-THA requires more often a different surgical approach and is at higher risk of complications. Despite the increased surgical burden post-operative PROMs are better in the peri-prosthetic fracture group, especially in cases not requiring reoperation.

LEVEL OF EVIDENCE

III, case-control study.

Effect of placement of acetabular prosthesis on hip joint function after THA

The good recovery of hip function after THA depends on reconstruction of acetabular prosthesis accurately. So we investigated the effect of acetabular prosthesis placement on hip joint function after THA and analyzed the clinical data of 432 patients with unilateral THA retrospectively . The patients were followed-up to evaluate the Harris score and hip range of motion (ROM). The hip ROM, the Harris score and the good rate of Harris score were compared between different groups. Comparison of the good rate of Harris score showed that 85%∼100% group of the rotation center horizontal position ratio was higher than >100% group; 80%∼120% group of the rotation center vertical position ratio was higher than >160% group; and the 90%∼110% group and 110%∼130% group of femoral offset ratio were higher than 90% and >130% groups. Comparison of Harris score showed that 85%∼100% and 70%∼85% groups of rotation center horizontal position ratio were higher than 70% and >100% groups; 80%∼120% group of rotation center vertical position ratio was the highest; and 90%∼110% group and 110%∼130% group of femoral offset ratio were higher than >130% and 90% groups. Comparison of hip ROM showed that 85%∼100% and 70%∼85% groups of the rotation center horizontal position ratio were higher than 70% and >100% groups; 80%∼120% group of the rotation center vertical position ratio was the highest; and hip ROM from high to low are 90%∼110%, 110%∼130%, >130% and 90% groups of femoral offset ratio. These findings indicated that during the early follow-up period of THA, if the horizontal position of femoral head rotation center was reconstructed in 0.85 to 1 times of healthy side when compared with reconstruction >1 times of the healthy side and if the vertical position of femoral head rotation center was reconstructed in 0.8 to 1.2 times of the healthy side when compared with reconstruction in >1.6 times of the healthy side, better hip function recovery and optimal hip ROM were obtained. The optimal reconstruction range of femoral offset is 0.9 to 1.3 times of the healthy side.

Incidence, risk factors and prognosis of transient pseudosubluxation after total hip arthroplasty

INTRODUCTION:

Pseudosubluxation is a transient separation of the prosthetic femoral head from the acetabular liner during the anaesthetic period after total hip arthroplasty (THA). However, little is known about the frequency, pathomechanism, risk factors or natural history.

METHODS:

To determine the incidence, direction of the displacement, risk factors and subsequent instability of pseudosubluxation, we evaluated 1099 primary cementless THAs (943 patients), which were performed during 8 years at one institution. Immediately after THA, postoperative radiographs were obtained for all hips. If a subluxation was noted, the operated hip was examined by fluoroscope within 1 hour of the detection and repeat radiographs were taken on the postoperative day 1.

RESULTS:

The pseudosubluxation was identified in 2.6% (28/1059). All of the 28 heads subluxed anteriorly and reduced in flexion-internal rotation. In multivariate analysis: (1) operative decrease of the femoral offset (odds ratio; 1.161 (95% confidence interval [CI]; 1.077-1.251), p = 0.001); and (2) medialisation of acetabular cup (odds ratio; 3.402 (95% CI; 1.482-7.813), p = 0.009) were found as risk factors for pseudosubluxation. None of the 28 hips dislocated during 3- to 8-year follow-up.

CONCLUSIONS:

Our results provide information about the incidence, risk factors and natural history of pseudosubluxation after primary THA. Surgeons should be aware of the risk of pseudosubluxation when performing THA in patients with coxa vara, who have a large femoral offset, and in those with dysplastic or deficient acetabulum, who have a lateral centre of rotation.

Patient Satisfaction Reporting After Total Hip Arthroplasty: A Systematic Review

This review evaluated the quality of patient satisfaction reporting after total hip arthroplasty. The initial search of the MEDLINE database yielded 755 studies. Twenty-four met the inclusion criteria. Most studies provided level III or IV evidence (n=15, 62.5%). The most common method used to assess satisfaction was the 10-point visual analog scale (7 studies, 29.2%), followed by an ordinal satisfaction scale (6 studies, 25.0%). The quality of evidence was poor, and the methods used to assess satisfaction were not standardized. Further research is needed to define the factors that affect patient satisfaction after total hip arthroplasty and how satisfaction is best measured. [Orthopedics. 2017; 40(3):e400-e404.].

Anterior subluxation after total hip replacement confirmed by radiographs: report of two cases

Demonstrable anterior subluxation of the femoral head after a total hip arthroplasty is a rare complication and is usually transient. Both a case of recurrent subluxation and a case of chronic subluxation are described in this paper, each one presenting with unexpected femoral head eccentricity in the acetabulum on radiograph. We show how this unusual complication can be successfully identified and treated.