We investigated the spinopelvic morphology and global sagittal balance of patients with a degenerative retrolisthesis or anterolisthesis. A total of 269 consecutive patients with a degenerative spondylolisthesis were included in this study. There were 95 men and 174 women with a mean age of 64.3 years (sd 10.5; 40 to 88). A total of 106 patients had a pure retrolisthesis (R group), 130 had a pure anterolisthesis (A group), and 33 had both (R+A group).

A backward slip was found in the upper lumbar levels (mostly L2 or L3) with an almost equal gender distribution in both the R and R+A groups. The pelvic incidence and sacral slope of the R group were significantly lower than those of the A (both p < 0.001) and R+A groups (both p < 0.001). The lumbar lordosis of the R+A group was significantly greater than that of the R (p = 0.025) and A groups (p = 0.014). The C7 plumb line of the R group was located more posteriorly than that of the A group (p = 0.023), but was no different from than that of the R+A group (p = 0.422). The location of C7 plumb line did not differ between the three groups (p = 0.068). The spinosacral angle of the R group was significantly smaller than that of the A group (p < 0.001) and R+A group (p < 0.001).

Our findings imply that there are two types of degenerative retrolisthesis: one occurs primarily as a result of degeneration in patients with low pelvic incidence, and the other occurs secondarily as a compensatory mechanism in patients with an anterolisthesis and high pelvic incidence.

Cite this article: Bone Joint J 2013;95-B:1244–9.

Background: There area some controversies about the need for revision of well fixed femoral stem during the revision total hip arthroplasty. The purpose of this study is to evaluate the state of unretrieved femoral stem, in revision total hip arthroplasty where only acetabular component was revised.

Methods: From January 1998 to December 2004, thirty-one patients underwent revision total hip arthroplasty whose well fixed femoral stem was retained and acetabular components revised. Twenty-six patients(29hips) with a minimum follow-up of three years were included in this study. Out of those twenty-six patients, sixteen patients(18hips) were male and ten patients(11hips) were female with an average age of 54.3 years for the study group. The average time from the primary operation until the revision surgery was 9.2 years and the average follow-up period after the revision was 5 years. The femoral head component was exchanged in all cases and same size femoral head component was used in eleven hips. The clinical results wee analyzed using Harris Hip Score, and the radiographs were reviewed for stability of acetabular components, femoral stem, and degree of osteolysis and radiolucent lines.

Results: The average Harris Hip score improved from 56.3 points preoperatively to 89.8 points postoperatively. Femoral stems were found to be stable in all hips. Sixteen hips(55.2%) showed evidence of osteolysis and seven hips(24.1%) showed non-progressive radiolucent lines. The osteolysis was detected at Gruen Zone I and VII in most of the affected hips except for two hips which showed distal osteolysis. The average life of femoral stem from primary operation until the final follow up varied from 10.8 years to 18.2 years, with the average being 14.2 years.

Conclusions: We recommended that well fixed, stable femoral components can be retained at the time of revision total hip arthroplasty.

Level of evidence: Therapeutic Level IV