Double acetabular wall--a misleading point for hip arthroplasty: an anatomical, radiological, clinical study

Imaging in Hip Arthroplasty Management-Part 1: Templating: Past, Present and Future

Hip arthroplasty is a frequently used procedure with high success rates. Its main indications are primary or secondary advanced osteoarthritis, due to acute fracture, osteonecrosis of the femoral head, and hip dysplasia. The goals of HA are to reduce pain and restore normal hip biomechanics, allowing a return to the patient’s normal activities. To reach those goals, the size of implants must suit, and their positioning must meet, quality criteria, which can be determined by preoperative imaging. Moreover, mechanical complications can be influenced by implant size and position, and could be avoided by precise preoperative templating. Templating used to rely on standard radiographs, but recently the use of EOS^® imaging and CT has been growing, given the 3D approach provided by these methods. However, there is no consensus on the optimal imaging work-up, which may have an impact on the outcomes of the procedure. This article reviews the current principles of templating, the various imaging techniques used for it, as well as their advantages and drawbacks, and their expected results.

Central acetabular osteophytes (CAO) are more prevalent in the borderline developmental dysplastic hip (BDDH) patients: a propensity-score matched CT study

Background

The acetabular fossa often showing the first signs of degeneration, Central acetabular osteophytes (CAO) have been increasingly recognized during hip arthroscopy. The purpose of this study was to investigate the condition of CAO in BDDH hips and compare cotyloid fossa size between the BDDH and the non-BDDH hips on CT images.

Methods

We performed a retrospective analysis of prospectively collected data of hip CT images of FAI or labral injury patients. A 1:2 propensity-score matched observational study comparing the linear length of cotyloid fossa was analyzed. Cotyloid fossa width (CFW) and cotyloid notch width (CNW) were measured on axial images, cotyloid fossa height (CFH) and cotyloid fossa depth (CFD) were measured on coronal images. Within the CAO patients, we performed central acetabular decompression (CAD) and then observed the morphology change in fossa.

Results

Propensity-score matching yielded 61 BDDH hips and 122 non-BDDH hips. BDDH hips had a higher prevalence of CAO and a decreased linear length of cotyloid fossa (CFW, CFH and CNW). In the BDDH group, 33 hips underwent CAD, postoperative CFW, CFH and CNW were significantly increased (p < .001 for all), and had no statistical difference compared with the non-BDDH hips (p = .193, p = .132, p = .421, respectively).

Conclusion

BDDH hips had a significantly higher prevalence of CAO than adequate acetabular coverage hips. After the procedure of CAD, BDDH hips were found to have acetabular parameters (CFW, CFH, CNW) and were restored to that of the control hips.

Hip preservation surgery and the acetabular fossa

As our understanding of hip function and disease improves, it is evident that the acetabular fossa has received little attention, despite it comprising over half of the acetabulum’s surface area and showing the first signs of degeneration. The fossa’s function is expected to be more than augmenting static stability with the ligamentum teres and being a templating landmark in arthroplasty. Indeed, the fossa, which is almost mature at 16 weeks of intrauterine development, plays a key role in hip development, enabling its nutrition through vascularization and synovial fluid, as well as the influx of chondrogenic stem/progenitor cells that build articular cartilage. The pulvinar, a fibrofatty tissue in the fossa, has the same developmental origin as the synovium and articular cartilage and is a biologically active area. Its unique anatomy allows for homogeneous distribution of the axial loads into the joint. It is composed of intra-articular adipose tissue (IAAT), which has adipocytes, fibroblasts, leucocytes, and abundant mast cells, which participate in the inflammatory cascade after an insult to the joint. Hence, the fossa and pulvinar should be considered in decision-making and surgical outcomes in hip preservation surgery, not only for their size, shape, and extent, but also for their biological capacity as a source of cytokines, immune cells, and chondrogenic stem cells.

Cite this article: Bone Joint Res 2020;9(12):857–869.

The Acetabular Fossa May Not Be Located at the True Center of the Acetabulum: A Detailed Analysis Using Preoperative CT Images

BACKGROUND

The acetabular fossa is thought to be located in the center of the acetabulum, and acetabular reaming in total hip arthroplasty is conventionally performed in the center of the fossa. However, the actual location of the fossa and the influence that hypoplasia or deformity may have on the position of the fossa are unknown. We hypothesized that the fossa is located in the center of the acetabulum, regardless of hypoplasia or deformity.

METHODS

Fifty patients with normal hips (normal hip group), 50 patients with dysplasia who underwent rotational acetabular osteotomy (dysplastic hip group), and 46 patients with osteoarthritis who underwent total hip arthroplasty (osteoarthritic hip group) were evaluated by computed tomography (CT) imaging. On the horizontal plane that passes through the center of the femoral head, the center line of the acetabulum was defined as the perpendicular bisector of the anterior and posterior rims of the acetabulum. The angle and distance of the center of the acetabular fossa in relation to the center line of the acetabulum were evaluated; furthermore, the center position of the fossa from the anterior margin of the acetabulum was calculated as a ratio relative to acetabular size. A 1-way analysis of variance was performed to compare measurements among the 3 groups.

RESULTS

The center of the acetabular fossa was positioned anteriorly to the center line of the acetabulum in all 3 groups. The mean center angle of the acetabular fossa was 14.0° ± 3.8°, 15.2° ± 5.6°, and 14.9° ± 5.5° in the normal, dysplastic, and osteoarthritic hip groups, respectively (p = 0.33). The mean center distance of the acetabular fossa was 5.6 ± 1.8, 5.8 ± 2.3, and 6.1 ± 2.2 mm, respectively (p = 0.55). The mean center position of the acetabular fossa was 38.8% ± 3.3%, 38.5% ± 4.2%, and 38.3% ± 3.9%, respectively (p = 0.71).

CONCLUSIONS

The center of the acetabular fossa is positioned anteriorly to the center of the acetabulum, and the positioning is affected by neither dysplasia nor osteoarthritis. The preconception that the center of the acetabulum corresponds to the center of the acetabular fossa may risk eccentric reaming, possibly damaging the anterior wall.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Cam Deformities and Limited Hip Range of Motion Are Associated With Early Osteoarthritic Changes in Adolescent Athletes: A Prospective Matched Cohort Study

BACKGROUND

The natural history of femoroacetabular impingement (FAI) remains incompletely understood. In particular, there is limited documentation of joint damage in adolescent patients with limited range of motion (LROM) of the hip, which is commonly associated with FAI.

PURPOSE

To evaluate changes in magnetic resonance imaging (MRI), radiographs, and clinical examinations over 5 years in a group of athletes from a wide variety of sports with asymptomatic LROM of the hip compared with matched controls.

STUDY DESIGN

Cohort study (prognosis); Level of evidence, 2.

METHODS

The authors screened 226 male and female athletes aged 12 to 18 years presenting for preparticipation sports physical examinations. Using a goniometer, we identified 13 participants with at least one hip having internal rotation <10° with the hip flexed to 90°. Overall, 21 of 26 hips (81%) had internal rotation <10°. These participants were age- and sex-matched to 13 controls with internal rotation >10°. At the time of enrollment, all participants were asymptomatic and underwent a complete hip examination and radiographic imaging with radiographs (anteroposterior [AP] and von Rosen views) and non-arthrogram MRI. Participants returned at 5-year follow-up and underwent repeat hip examinations, imaging (AP and lateral radiographs and non-arthrogram MRI), and hip function questionnaires. MRI scans were classified as "normal" versus "abnormal" based on the presence of any of 13 scored chondral, labral, or osseous abnormalities. Comparisons between the LROM group and control group were performed using generalized linear models (either linear, logistic, or log-binomial regression as appropriate for the outcome) with generalized estimating equations to account for the within-participant correlation due to patients having both hips included. Relative risk (RR) estimates are reported with 95% CIs.

RESULTS

At the time of study enrollment, 16 of 26 hips (62%) in the LROM group had abnormal MRI findings within the acetabular labrum or cartilage compared with 8 of 26 hips (31%) in the control group (RR, 2.0; 95% CI, 0.95-4.2; P = .067). The mean alpha angle measured from radial MRI sequences was 58° in the LROM group versus 44° in the control group ( P < .0001). In the LROM group, 13 of 26 hips (50%) had a positive anterior impingement sign, whereas 0 of 26 hips (0%) had a positive anterior impingement sign in the control group. At 5-year follow-up, 18 of 19 hips (95%) in the LROM group had abnormal MRI findings compared with 14 of 26 hips (54%) in the control group (RR, 1.7; 95% CI, 1.1-2.7; P = .014). New or progressive findings were documented on MRI in 15 of 20 hips in the LROM group compared with 8 of 26 hips in the control group (RR, 2.4; 95% CI, 1.2-4.8; P = .011). Six of 22 hips (27%) in the LROM group progressed from Tönnis grade 0 to Tönnis grade 1 in degenerative changes, whereas all 26 hips in the control group remained at Tönnis grade 0 on hip radiographs. In the LROM group, 11 of 22 hips (50%) had a positive anterior impingement sign, whereas 1 of 26 hips (4%) had a positive anterior impingement sign in the control group. A cam deformity (alpha angle >55° on lateral radiographs) was present in 20 of 22 hips (91%) in the LROM group and 12 of 26 hips (46%) in the control group ( P = .0165). The following variables at baseline were associated with an increased risk of degenerative changes at 5-year follow-up for the entire cohort: decreased hip internal rotation, positive anterior impingement sign, decreased hip flexion, increased alpha angle, and presence of a cam lesion.

CONCLUSION

At 5 years, young athletes with LROM of the hip showed increased progressive degenerative changes on MRI and radiographs compared with matched controls. Although the majority of these participants remained asymptomatic, those with features of FAI had radiographic findings consistent with early osteoarthritis. These outcomes suggest that more aggressive screening and counseling of young active patients may be helpful to prevent hip osteoarthritis in those with FAI.

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

BACKGROUND

Magnetic resonance arthrogram (MRA) with radial cuts is presently the best available preoperative imaging study to evaluate chondrolabral lesions in the setting of femoroacetabular impingement (FAI). Existing followup studies for surgical treatment of FAI have evaluated predictors of treatment failure based on preoperative clinical examination, intraoperative findings, and conventional radiography. However, to our knowledge, no study has examined whether any preoperative findings on MRA images might be associated with failure of surgical treatment of FAI in the long term.

QUESTIONS/PURPOSES

The purposes of this study were (1) to identify the preoperative MRA findings that are associated with conversion to THA, any progression of osteoarthritis, and/or a Harris hip score of < 80 points after acetabuloplasty and/or osteochondroplasty of the femoral head-neck junction through a surgical hip dislocation (SHD) for FAI at a minimum 10-year followup; and (2) identify the age of patients with symptomatic FAI when these secondary degenerative findings were detected on preoperative radial MRAs.

METHODS

We retrospectively studied 121 patients (146 hips) who underwent acetabuloplasty and/or osteochondroplasty of the femoral head-neck junction through SHD for symptomatic anterior FAI between July 2001 and March 2003. We excluded 35 patients (37 hips) with secondary FAI after previous surgery and 11 patients (12 hips) with Legg-Calvé-Perthes disease. All patients underwent preoperative MRA to further specify chondrolabral lesions except in 19 patients (32 hips) including 17 patients (20 hips) who presented with an MRI from an external institution taken with a different protocol, 10 patients with no preoperative MRA because the patients had already been operated on the contralateral side with a similar appearance, and two patients (two hips) refused MRA because of claustrophobia. This resulted in 56 patients (65 hips) with idiopathic FAI and a preoperative MRA. Of those, three patients (three hips) did not have minimal 10-year followup (one patient died; two hips with followup between 5 and 6 years). The remaining patients were evaluated clinically and radiographically at a mean followup of 11 years (range, 10-13 years). Thirteen pathologic radiographic findings on the preoperative MRA were evaluated for an association with the following endpoints using Cox regression analysis: conversion to THA, radiographic evidence of any progression of osteoarthritis, and/or a Harris hip score of < 80. The age of the patient when each degenerative pattern was found on the preoperative MRA was recorded.

RESULTS

The following MRI findings were associated with one or more of our predefined failure endpoints: cartilage damage exceeding 60° of the circumference had a hazard ratio (HR) of 4.6 (95% confidence interval [CI], 3.6-5.6; p = 0.003) compared with a damage of less than 60°, presence of an acetabular rim cyst had a HR of 4.1 (95% CI, 3.1-5.2; p = 0.008) compared with hips without these cysts, and presence of a sabertooth osteophyte had a HR of 3.2 (95% CI, 2.3-4.2; p = 0.013) compared with hips without a sabertooth osteophyte. The degenerative pattern associated with the youngest patient age when detected on preoperative MRA was the sabertooth osteophyte (lower quartile 27 years) followed by cartilage damage exceeding 60° of the circumference (28 years) and the presence of an acetabular rim bone cyst (31 years).

CONCLUSIONS

Preoperative MRAs with radial cuts reveal important findings that may be associated with future failure of surgical treatment for FAI. Most of these factors are not visible on conventional radiographs or standard hip MRIs. Preoperative MRA evaluation is therefore strongly recommended on a routine basis for patients undergoing these procedures. Findings associated with conversion to arthroplasty, radiographic evidence of any progression of osteoarthritis, and/or a Harris hip score of < 80 points should be incorporated into the decision-making process in patients being evaluated for joint-preserving hip surgery.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Influence of pelvic tilt on functional acetabular orientation

BACKGROUND

Pelvic tilt influences acetabular orientation (AO). Anatomical AO can be measured in relation to the anterior pelvic plane (APP), functional AO can be calculated relative to table's plane.

OBJECTIVE

To assess to what extent functional AO is determined by pelvic tilt and if APP and table plane give equal information for correct AO.

METHODS

AO was evaluated by computed tomography (CT) scans of 138 patients. Pelvic tilt, anatomical and functional AO were measured, differences between the two reference planes were calculated.

RESULTS

Anatomical and functional acetabular anteversion (AA) were found to be different in 21% of individuals with an enhanced extent of pelvic tilt. Functional AA was increased compared to anatomical AA at high posterior pelvic tilt (p < 0.001). Enlarged anterior tilting of the pelvis reduced APP-related AA (p < 0.002). Anatomical AA positively correlated with pelvic tilt, particularly in females (p < 0.01, correlation coefficient = 0.698, R2 = 0.523).

CONCLUSIONS

APP and table plane do not provide equal information about AO at enhanced pelvic tilt. Functional orientation of the acetabulum is dependent on pelvic tilt, which itself is influenced by anatomical AA and should therefore be analyzed for precise AO.

Calculating the hip center of rotation using contralateral pelvic anatomy

Failure to place an artificial hip in the optimal center of rotation results in poor hip function and costly complications. The aim of this study was to develop robust methodology to estimate hip center of rotation (hCoR) from preoperative computed tomography (CT) scans, using contralateral anatomy, in patients with unilateral diseased hips. Ten patients (five male, five female) with normal pelvic anatomy, and one patient with a unilateral dysplastic acetabulum were recruited from the London Implant Retrieval center image bank. 3D models of each pelvis were generated using commercial software. Two methods for estimation of hCoR were compared. Method 1 used a mirroring technique alone. Method 2 utilized mirroring and automatic alignment. Predicted versus actual hCoR co-ordinates were compared using intraclass correlation coefficients and paired T-tests. Both methods predicted hCoR with excellent agreement to original co-ordinates (>0.9) in all axes. Both techniques allowed prediction of the hCoR within ± 5 mm in all axes. Both techniques provided useful clinical information for planning acetabular reconstruction in patients with unilateral defects. Method 1 was less complex and is suitable for patients with developmental and degenerative pathologies. Method 2 may provide greater accuracy in a discrete group of patients with normal development prior to pathology (e.g., acetabular fractures). © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1077-1083, 2016.

Senior Managed Care System for Hip Fracture in the United States

Background

It is debatable whether a managed care model would affect the quality of care and length of hospital stay in the treatment of hip fractures in elderly patients.

Methods

This prospective study was undertaken to determine whether or not a managed care critical pathway tool shortened hospital stay in a group of 102 senior patients with fractures of the hip during follow-up. We compared our study findings with two equivalent populations of senior hip fracture patients not treated using a critical care pathway concerning specific markers of quality.

Results

The managed care group had a 9% mortality rate, 95% return to prefracture living and 63% return to ambulatory status. The rates compared favorably with previous studies. The quality of care provided before and after the critical pathway was equivalent, while the post-pathway length of stay dropped 30%.

Conclusions

The proposed care protocol is recommended to shorten hospital stay in elderly patients with hip fractures.

A new method for tibial torsion measurement by computerized tomography

BACKGROUND

Computerized tomography (CT) is the gold standard technique for tibial torsion assessment. This study compared two methods of tibial torsion assessment and proposed a new method, which could be of value in cases of abnormal fibular changes.

METHODS

The CT-scanograms of 60 participants were assessed by using two different techniques, differed in determination of the distal tibial axis.

RESULTS

The interobserver reliability was 0.861 and 0.863 in the first and second methods, respectively. The intraobserver reliability in both measurement methods was 0.868.

CONCLUSIONS

We proposed a reliable method, independent of the fibular midpoint, in assessment of tibial torsion by CT.

Anterior D-rod and titanium mesh fixation for acute mid-lumbar burst fracture with incomplete neurologic deficits: A prospective study of 56 consecutive patients

BACKGROUND

Anterior decompression and reconstruction have gained wide acceptance as viable alternatives for unstable mid-lumbar burst fracture, but there are no mid and long term prospective studies regarding clinical and radiologic results of mid-lumbar burst fractures.

MATERIALS AND METHODS

An Institutional Review Board-approved prospective study of 56 consecutive patients of mid-lumbar burst fractures with a load-sharing score of 7 or more treated with anterior plating was carried out. All patients were evaluated for radiologic and clinical outcomes. The fusion status, spinal canal compromise, segmental kyphotic angle (SKA), vertebral body height loss (VBHL), and adjacent segment degeneration was examined for radiologic outcome, whereas the American Spinal Injury Association scale, the visual analog scale (VAS), and the employment status were used for clinical evaluation.

RESULTS

The patients underwent clinical and radiologic followup for at least 5 years after the surgery. At the last followup, there was no case of internal fixation failure, adjacent segment degeneration, and other complications. Interbody fusion was achieved in all cases. The average fusion time was 4.5 months. No patient suffered neurological deterioration and the average neurologic recovery was 1.3 grades on final observation. Based on VAS pain scores, canal compromise, percentage of VBHL and SKA, the difference was statistically significant between the preoperative period and postoperative or final followup (P < 0.05). Results at postoperative and final followup were better than the preoperative period. However, the difference was not significant between postoperative and final followup (P > 0.05). Thirty-four patients who were employed before the injury returned to work after the operation, 15 had changed to less strenuous work.

CONCLUSION

Good mid term clinicoradiological results of anterior decompression with D-rod and titanium mesh fixation for suitable patients with mid-lumbar burst fractures with incomplete neurologic deficits can be achieved. The incident rate of complications was low. D-rod is a reliable implant and has some potential advantages in L4 vertebral fractures.

Anterior decompression with single segmental spinal interbody fusion for Denis type B thoracolumbar burst fracture: a midterm follow-up study

PURPOSE

Our goal was to observe the midterm results of a case series of Denis type B thoracolumbar burst fracture treated with anterior decompression with single segmental spinal Interbody fusion.

METHODS

Twenty patients with Denis type B thoracolumbar burst fractures underwent anterior decompression with single segmental spinal Interbody fusion. They underwent clinical and radiologic follow-up for at least three years after the surgery.

RESULTS

The mean follow-up period lasted 57 months. To the last follow-up, there were no cases of internal fixation loosening, failure and other complications. Titanium mesh or interbody bone grafts were in good position. Spinal kyphosis was not observed. Interbody fusion was achieved for all cases. The average fusion time was 4.5 months. Based on visual analogue scale (VAS) pain scores, percentage of vertebral body height loss and Cobb angle, the difference was statistically significant between the preoperative period and postoperative one year or final follow-up (P < 0.05). Results at postoperative one year and final follow-up were better than the preoperative period. However, the difference was not significant between postoperative one year and final follow-up (P > 0.05).

CONCLUSIONS

Good midterm results on clinical and radiologic evaluation of anterior decompression with single segmental spinal Interbody fusion for suitable patients with Denis type B thoracolumbar burst fracture can be achieved. The incident rate of relative complications is low.