Central acetabular osteophyte (saber tooth sign), one of the earliest signs of osteoarthritis of the hip joint

Background Protrusio acetabuli is a rare anatomic pattern of the hip in which the femoral head protrudes into the true pelvis. The increased depth of the hip and the excessive size of the lunate surface typically lead to severe pincertype femoroacetabular impingement (FAI); however, to our knowledge, there are no published mid-or long-term studies on results of circumferential acetabular rim trimming through a surgical hip dislocation for patients with this condition. Questions/purposes (1) What is the 10-year survivorship of the hips treated with circumferential rim trimming through a surgical hip dislocation compared with a control group of hips that underwent surgery for pincer FAI but that did not have protrusio acetabuli? (2) What are the factors that were associated with a decreased likelihood of survivorship in those hips with the following endpoints: total hip arthroplasty, Merle d'Aubigné score of less than 15, and/or radiographic progression of osteoarthritis (OA)? (3) Does the radiographic pattern of degeneration differ between the two groups?Methods We performed a case-control study comparing two groups: a protrusio group (32 patients [39 hips]) and a control group (66 patients [86 hips]). The control group consisted of hips treated with a surgical hip dislocation for pincer FAI and did not include hips with a positive protrusio sign or a lateral center-edge angle [ 39°. The study group did not differ from the control group regarding the preoperative Tönnis OA score, age, and body mass index. However, the study group had more women, decreased mean height and weight, and lower preoperative Merle d'Aubigné-Postel scores, which were inherent differences at the time of first presentation. During the period in question, the indication for performing these procedures was a painfully restricted range of motion in flexion and internal rotation (positive impingement sign). The mean followup of the protrusio group (9 ± 5 years [range, 2-18 years]) did not differ from the control group (11 ± 1 years [range, 10-13 years], p = 0.109). At the respective minimum followup intervals in the underlying database from which cases and control subjects were drawn, followup was 100% for patients with protrusion who underwent FAI surgery and 97% for patients with FAI who underwent surgery for other anatomic patterns (three of 86 hips). We assessed the Merle d'Aubigné-Postel score, Harris hip score, WOMAC, and UCLA activity score at latest followup. A Kaplan-Meier survivorship analysis of the hip was calculated if any of the following endpoints for both groups occurred: conversion to total hip arthroplasty, a Merle d'Aubigné-Postel score \ 15, and/or radiographic progression of OA. Differences in survivorship were analyzed using the log-rank test. Results At 10-year followup, we found a decreased survivorship of the hip for the protrusio group (51% [95% confidence interval {CI}, 34%-67%]) compared with the control group (83% [95% CI, 75%-91%], p \ 0.001) with -016-4918-9 Clinical Orthopaedics and Related Research ...

“…3). In the protrusio group, progression of saber tooth osteophytes [23] (from 6% to 29%, p = 0.014) and osteophytes at the lateral acetabular edge (from 15% to 52%, p = 0.002) was found.…”

Section: Resultsmentioning

confidence: 93%

Hips With Protrusio Acetabuli Are at Increased Risk for Failure After Femoroacetabular Impingement Surgery: A 10-year Followup

Hanke

Steppacher

Zurmühle

et al. 2016

“…3B) [36]. In osteoarthritic hips, osteophytes are present at the anterior rim of the acetabulum, which obscure the AAN, and the cotyloid fossa frequently is covered by a bony spur, a so-called central osteophyte [25], which obscures the TAN. We measured acetabular anteversion at the margin of the native acetabulum excluding the anterior osteophyte and acetabular abduction at the teardrop excluding the central osteophyte.…”

Section: Methodsmentioning

confidence: 99%

Acetabular Component Positioning Using Anatomic Landmarks of the Acetabulum

Yoo

Lee

et al. 2012

Background The acetabular cup should be properly oriented to prevent dislocation and to reduce wear. However, achieving proper cup placement is challenging with potentially large variations of cup position. We propose a new technique to position the acetabular cup. Questions/Purposes We used this technique, then determined actual cup position and subsequent dislocation rate. Methods We measured acetabular abduction (a°) and anteversion (b°) on preoperative CT scans in 46 patients (50 hips) scheduled for THA. During the operation, we identified the transverse acetabular notch (TAN) and anterior acetabular notch (AAN), a notch at the anterior acetabular margin. We then marked two reference points for 40°abduction at the acetabular rim: the superior point, which is opposite the TAN, and the inferior point at |a À 40| mm inside (when a was [ 40°) or outside the TAN (when a was \ 40°). We also marked two reference points for 15°anteversion: the posterior point opposite the AAN and the anterior point at |b À 15| mm inside (when b was \ 15°) or outside the AAN (when b was [ 15°). During cup insertion, we aligned cup abduction to the line between the superior and inferior points and cup anteversion to the line between the anterior and posterior points. We measured cup abduction and anteversion and evaluated the dislocation rate. One patient was lost to followup before 60 months; the minimum followup for the other 45 patients was 60 months (mean, 62.8 months; range, 60-65 months). Results The mean cup abduction was 40°(range, 32°-47°) and the mean cup anteversion was 17°(range, 8°-25°). No dislocation occurred postoperatively in 49 hips (45 patients) for a minimum of 5 years followup.

“…The presence of osteoarthritis, reflected by a decrease in joint space width (Tönnis Grade [ 0), is a consistently identified negative predictor for surgical outcome [31,45,61,62]. Often, subtle secondary degenerative findings are present before joint space narrowing or loss of cartilage [42,60]. These findings, including chondrolabral lesions, paralabral cysts, and subtle osteophytes, are more reliably detected on radial MRI of the hip [28,34,60].…”

Section: Introductionmentioning

confidence: 99%

What MRI Findings Predict Failure 10 Years After Surgery for Femoroacetabular Impingement?

Hanke

Steppacher

Anwander

et al. 2017