Journal of Hip Preservation Surgery Vol. 5, No. 1, pp. 66–72 doi: 10.1093/jhps/hnx031 Advance Access Publication 10 October 2017 Research article Clinical outcomes of patients with symptomatic acetabular rim fractures after arthroscopic FAI treatment 1 2 2 Brian D. Giordano , Carlos Suarez-Ahedo , Chengcheng Gui , 2 2 2,3 Nader Darwish , Parth Lodhia and Benjamin G. Domb * University of Rochester Medical Center, American Hip Institute and Hinsdale Orthopaedics, 550 W. Ogden Ave., Hinsdale, IL 6052 *Correspondence to: B. G. Domb. E-mail: firstname.lastname@example.org Submitted 16 January 2017; Revised 5 June 2017; revised version accepted 30 July 2017 ABSTRACT This study aims to investigate the inﬂuence of the acetabular rim fractures on outcomes of hip arthroscopy at minimum 2-year follow-up. Between January 2009 and August 2012, data were prospectively collected on all pa- tients undergoing hip arthroscopy. Anatomic ﬁndings, including presence of rim fractures, were recorded intrao- peratively. Patients were assessed preoperatively and at 3 months, 1 year and minimum 2 years postoperatively with four patient-reported outcome measures: modiﬁed Harris Hip Score, Non-Arthritic Hip Score, Hip Outcome Score-Activities of Daily Living and Hip Outcome Score-Sport Speciﬁc Subscales. Pain was estimated using a visual analog scale. Satisfaction was measured on a scale from 0 to 10. Patients with rim fractures were identiﬁed and retrospectively matched to a control group based on gender, BMI category, and age at surgery within 3 years and compared in terms of demographic factors, intraoperative ﬁndings, procedures and outcomes. Twenty-one patients with rim fractures were matched to a control group of 21 patients with symptomatic femo- roacetabular impingement without rim fractures. No signiﬁcant differences were detected with respect to demo- graphic characteristics, surgical procedures (besides the removal of rim fractures), or in terms of preoperative, postoperative, or improvement in patient-reported outcome scores and satisfaction. The presence or absence of an acetabular rim fracture does not signiﬁcantly inﬂuence clinical outcomes at minimum 2-year follow-up after hip arthroscopy. Case–control study design is used in this study. INTRODUCTION Rim fractures have been described as vertically oriented gaps between the fragment and stable rim, which magnetic Ossicles around the hip were first described in 1737 by Albinus and were termed ‘os acetabuli’ by Krause in 1876 resonance imaging (MRI) has shown to be composed of labrum, articular cartilage and bone [6, 7]. . Currently, they are referred to as unfused secondary ossification centers or rim fractures in patients with hip Typically, the treatment of these fragments includes complete excision in cases where the center edge (CE) dysplasia, previous trauma, osteochondritis dissecans, retroverted acetabuli and femoroacetabular impingement angles are adequate, with or without the fragment (lateral CE angle> 20–25 , anterior CE angle> 20 ). In those (FAI) [1–4]. It is believed that they are a consequence of the forces transmitted to the acetabular bony edge creating cases where the CE angle is <20–25 on coronal imaging (anteroposterior pelvis) and <20 on a false profile view, a fracture [1–4]. However, previous in vitro studies have demonstrated that compressive forces result in mineraliza- partial resection and internal fixation of the remaining por- tion is considered. Fixation of the entire fragment is con- tion of the acetabular labrum, resulting in a painful hip mimicking or coexisting with FAI [5, 6]. sidered if the fragment is necessary for normal coverage, V C The Author 2017. Published by Oxford University Press. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by- nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact email@example.com Downloaded from https://academic.oup.com/jhps/article-abstract/5/1/66/4430316 by Ed 'DeepDyve' Gillespie user on 16 March 2018 Clinical outcomes of patients with symptomatic acetabular rim fractures 67 and the hip would be dysplastic without the fragment. Some review board approval was obtained prior to initiation of studies have shown iatrogenic dislocations and subluxations this study. after excessive arthroscopic rim resections [8–11]. This study provides the first case–control study report- Statistical analyses ing on the effect of acetabular rim fractures on 2-year out- Patients with and without rim fractures were retrospect- comes following arthroscopic treatment of the hip. ively matched based on gender, BMI category and age at The first question to be answered in this study is what surgery within 3 years and compared in terms of demo- are the outcomes of arthroscopic treatment of FAI accom- graphic factors, intraoperative findings, procedures and panied by removal of an acetabular rim fracture? The se- outcomes (Table I). An a priori power analysis showed cond purpose of this study was to investigate the influence that at least 17 patients per group were needed to rule out of the acetabular rim fractures on outcomes of arthroscopic type II error when comparing PRO scores between the hip preservation surgery for FAI at minimum 2-year two groups, assuming a 10-point difference in the means follow-up, in comparison with patients with FAI without and a 10-point standard deviation in both groups. P values rim fractures. We hypothesized that, since acetabular rim <0.05 were considered statistically significant. fractures were a potential underlying cause of the patient’s preoperative symptoms, patients treated for acetabular rim RESULTS fractures would demonstrate a greater improvement in out- The study period and matching criteria yielded 21 patients comes, compared with patients who did not have rim with rim fractures and 21 patients without rim fractures. fractures. No significant differences were detected in terms of demo- graphic characteristics, including age at surgery, BMI, worker’s compensation claim, or conversion to total hip MATERIALS AND METHODS arthroplasty (Table II). No other intraoperative findings, other than the acetabular rim fractures themselves, demon- Patient selection strated significant or nearly significant differences between A matched-pair controlled case study, using retrospectively groups (Table II). Of the 21 patients with rim fractures, 20 collected data, was conducted for patients who underwent underwent fragment or loose body removal and 1 patient arthroscopic hip preservation surgery between January underwent to partial resection of the fragment, while none 2009 and August 2012. Anatomic findings, including pres- of the patients without rim fractures required this proced- ence of rim fractures, were recorded intraoperatively. ure (P< 0.0001). The mean P values of the PRO scores Labral tears were described using the Seldes classification comparing both groups preoperatively showed no sig- system . Acetabular chondral lesions were described nificant differences (Fig. 1), but we were expecting a using the acetabular labrum articular disruption (ALAD) difference after the surgery. Patients with rim frac-  and Outerbridge classification systems . Femoral tures demonstrate higher VAS at 1-year post-surgery head chondral lesions were described using the (P ¼ 0.047) but at 2 years of follow-up, this difference was Outerbridge classification system. Ligamentum teres tears not statistically significant (P ¼ 0.1) (Fig. 2). We took the were described using the descriptive  and Gray and five most performed procedures on both groups and Villar classification systems . All procedures were per- formed by the senior surgeon (BGD). Patients were as- Table I. Matching criteria sessed preoperatively and at 3 months, 1 year and minimum 2 years postoperatively with four patient- Matching criterion Categories or range reported outcome (PRO) measures: modified Harris Hip Gender Male Score (mHHS), Non-Arthritic Hip Score (NAHS), Hip Outcome Score-Activities of Daily Living (HOS-ADL) and Female Hip Outcome Score-Sport Specific Subscales (HOS-SSS). BMI Normal (<25 kg/cm ) Pain was estimated on the visual analog scale (VAS). Satisfaction with surgery was measured with the question Overweight (25 kg/cm ‘How satisfied are you with your surgery results? (1 ¼ not and <30 kg/cm ) at all, 10¼ the best it could be)’. We performed preopera- Obese (39 kg/cm ) tive and postoperative X-ray measurement of the Lateral Center Edge Angle (LCEA), Anterior Center Edge Angle Age Within 3 years (ACEA) and COS (Cross-Over Sign). Investigational Downloaded from https://academic.oup.com/jhps/article-abstract/5/1/66/4430316 by Ed 'DeepDyve' Gillespie user on 16 March 2018 68 B. D. Giordano et al. Table II. Demographic factors Rim fracture No rim fracture P value Number of patients 21 21 Gender (male) 15 (71.43%) 15 (71.43%) 1 Laterality (right) 14 (66.67%) 11 (52.38%) 0.3 Age at surgery (years) 33 (15.6–49.1) 33 (15.7–49.2) 1 Height (in.) 68.5 (62–77) 69.4 (63–75) 0.5 Weight (lb) 178.8 (120–277) 172.7 (100–260) 0.7 BMI (kg/cm ) 26.5 (19.4–36.7) 24.9 (17.7–33) 0.2 Workers’ compensation claim 0 (0%) 2 (9.52%) 0.5 Follow-up time (months) 27 (24.2–38.5) 26 (23.5–34.6) 0.4 Conversion to THA/BHR 0 (0%) 0 (0%) 0.9 Percentages and ranges are given in parentheses. Fig. 1. Preoperative PRO scores and VAS comparing the group with rim fractures versus the group without rim fractures. measure the P values at 2 years of follow-up showing that compared with the group of patients with rim fractures there was no statistically significant difference between (Fig. 3A–D). When we compared the P values of the pre- groups in terms of postoperative, or improvement in operative and postoperative X-ray measurements LCEA, PRO scores, or in satisfaction. Nevertheless, we found that ACEA and COS the difference between groups was not the patients without rim fractures had better PRO scores statistically significant (Fig. 4). Downloaded from https://academic.oup.com/jhps/article-abstract/5/1/66/4430316 by Ed 'DeepDyve' Gillespie user on 16 March 2018 Clinical outcomes of patients with symptomatic acetabular rim fractures 69 Fig. 2. PRO scores and VAS at preoperative and postoperative (3 months, 1 year and 2 years) time points. DISCUSSION and significant effect of acetabular rim fractures on patient The function of the ‘os acetabuli’, or acetabular rim frac- outcomes was not observed. ture, in the acetabular anatomy remains unclear . One Our study has some important limitations. First, our se- hypothesis is that ‘os acetabuli’ and rim fractures are the re- lection of patients for rim fractures removal is mostly based sult of abnormal acetabular development in congenital hip on the symptoms and maybe the symptoms are from the dysplasia or Perthes disease [1–3], or the consequence of FAI. Second, we analyzed function with the mHHS, al- stress fractures from repetitive contact of the femoral neck though this PRO has been validated in hip arthroscopy, its against the acetabular rim in pincer impingment [2, 7, 8]. reliability needs to be tested . The HOOS, which we It has been described by Martı´nez et al.  that in the could only assess at latest follow-up, is better suited for presence of pincer type impingement, ‘os acetabuli’ and evaluation of outcomes in the younger, more active popu- rim fractures may present with a prevalence of 3.6%. lation undergoing hip arthroscopy. Finally, we did not Jackson et al.  identified an amorphous calcification de- have consistent documentation of chondromalacia at posited in the anterosuperior labrum in 16 patients at the arthroscopy in this retrospective study. However, the four time of arthroscopy. All patients had labral tears and all pa- subgroups were comparable in terms of presence of pre- tients had at least one component of FAI. operative radiographic osteoarthritis, all of our cases had a We hypothesized that patients with FAI and acetabular To¨nnis grade 1. rim fractures may have better outcomes after arthroscopic Arthroscopic techniques may be employed to treat FAI, treatment, considering that the acetabular rim fracture as well as acetabular bony fragments associated with FAI. could be an underlying factor that increased the patients’ Given that optimal surgical treatment has not been specified symptoms preoperatively. However, the current study did in the literature, excision, fixation, or a combination thereof not demonstrate any statistically significant differences in are the main types of treatment options. In 2009, Epstein PRO scores or conversion to total hip replacement at min- et al.  reported one case of arthroscopic internal fixation imum 2-year follow-up between patients treated for rim of an unstable fracture of the acetabular rim after removal of fractures and patients who did not have rim fractures. the fibrocartilaginous junction. In 2011, Larson et al.  Perhaps due to the larger number of structures implicated performed an arthroscopic partial excision and internal fix- in FAI and the variable pattern of impingement, a specific ation, both with excellent results at 2 years of follow-up. Downloaded from https://academic.oup.com/jhps/article-abstract/5/1/66/4430316 by Ed 'DeepDyve' Gillespie user on 16 March 2018 70 B. D. Giordano et al. Fig. 3. (A) PRO scores and VAS at 2-year follow in Acetabuloplasty patients comparing the group with rim fractures versus the group without rim fractures. (B) PRO scores and VAS at 2-year follow in femoral osteoplasty patients comparing the group with rim frac- tures versus the group without rim fractures. (C) PRO scores and VAS at 2-year follow in Removal of Loose Body patients comparing the group with rim fractures versus the group without rim fractures. (D) PRO scores and VAS at 2-year follow in Iliopsoas Release pa- tients comparing the group with rim fractures versus the group without rim fractures. (E) PRO scores and VAS at 2-year follow in Labral Repair patients comparing the group with rim fractures versus the group without rim fractures. Downloaded from https://academic.oup.com/jhps/article-abstract/5/1/66/4430316 by Ed 'DeepDyve' Gillespie user on 16 March 2018 Clinical outcomes of patients with symptomatic acetabular rim fractures 71 Fig. 3. Continued Fig. 4. X-ray measurements at preoperative and postoperative time points comparing the group with rim fractures versus the group without rim fractures. Downloaded from https://academic.oup.com/jhps/article-abstract/5/1/66/4430316 by Ed 'DeepDyve' Gillespie user on 16 March 2018 72 B. D. Giordano et al. CONCLUSIONS 3. Lindstrom JR, Ponseti IV, Wenger DR. Acetabular development after reduction in congenital dislocation of the hip. J Bone Joint The presence or absence of an acetabular rim fracture does Surg Am 1979; 61: 112–8. not appear to significantly impact patient reported clinical 4. Larson CM, Stone RM. The rarely encountered rim fracture that outcomes at minimum of 2 years following arthroscopic contributes to both femoroacetabular impingement and hip sta- hip preservation surgery. The outcomes of this investiga- bility: a report of 2 cases of arthroscopic partial excision and in- tion may contribute to future efforts to identify optimal ternal ﬁxation. Arthroscopy 2011; 27: 1018–22. treatments for acetabular rim fractures. 5. Cooke WR, Gill HS, Murray DW, Ostlere SJ. Discrete mineralisa- tion of the acetabular labrum: a novel marker of femoroacetabular impingement?. Br J Radiol 2013; 86: 20120182. ACKNOWLEDGEMENTS 6. Jackson TJ, Stake CE, Stone JC et al. Radiographic, histologic, and arthroscopic ﬁndings in amorphous calciﬁcations of the hip The authors thank Tomas Llano MD. This study was labrum. Arthroscopy 2014; 30: 456–61. performed at the American Hip Institute. This study was 7. Martı´nez AE, Li SM, Ganz R, Beck M. Os acetabula in femoro- approved by the Institutional Review Board (IRB ID: 5276). acetabular impingement: stress fracture or unfused secondary os- siﬁcation centre of the acetabular rim?. Hip Int 2006; 16: 281–6. FUNDING 8. Rafols C, Monckeberg JE, Numair J. Unusual bilateral rim frac- This research did not receive any speciﬁc grant from fund- ture in femoroacetabular impingement. Case Rep Orthop 2015; ing agencies in the public, commercial, or not-for-proﬁt 2015: 1–4. 9. Benali Y, Katthagen BD. Hip subluxation as a complication of sectors. arthroscopic debridement. Arthroscopy 2009; 25: 405–7. 10. Matsuda DK. Acute iatrogenic dislocation following hip impinge- CONFLICT OF INTEREST STATEMENT ment arthroscopic surgery. Arthroscopy 2009; 25: 400–4. Brian D. Giordano is a paid consultant to Arthrex Inc., col- 11. Ranawat AS, McClincy M, Sekiya JK. Anterior dislocation of the lects research support, and royalties. Benjamin G. Domb hip after arthroscopy in a patient with capsular laxity of the hip. A reports personal fees and other from Arthrex, other from case report. J Bone Joint Surg Am 2009; 91: 1992-197. Breg, other from ATI, personal fees and other from Pacira, 12. Seldes RM, Tan V, Hunt J et al. Anatomy, histological features, personal fees and other from Stryker, personal fees from and vascularity of the adult acetabular labrum. Clin Orthop 2001; Orthomerica, personal fees from DJO Global, personal 382: 232–40. fees from Amplitude, personal fees from Medacta, outside 13. Callaghan JJ, Rosenberg AG, Rubash HE. The Adult Hip, 2nd edn. Philadelphia, Pennsylvania: Lippincott Williams & Wilkins, the submitted work; and Dr. Domb is a board member for the American Hip Institute, which funds research and is 14. Outerbridge RE. The etiology of chondromalacia patella. J Bone the institute where our studies are performed. Dr. Domb Joint Surg 1961; 43B: 752–7. is also a board member at the AANA Learning Center 15. Botser IB, Martin DE, Stout CE, Domb BG. Tears of the ligamen- Committee and Arthroscopy Journal. tum teres: prevalence in hip arthroscopy using 2 classiﬁcation sys- tems. Am J Sports Med 2011; 39: 117S–25S. REFERENCES 16. Gray AJ, Villar RN. The ligamentum teres of the hip: an arthro- scopic classiﬁcation of its pathology. Arthroscopy 1997; 13: 1. Klaue K, Durnin CW, Ganz R. The acetabular rim syndrome. A 575–8. clinical presentation of dysplasia of the hip. J Bone Joint Surg Br 17. Kemp JL,Collins NJ,MakdissiM et al.Hip arthroscopyfor 1991; 73: 423–9. intra-articular pathology: a systematic review of outcomes with 2. Epstein NJ, Safran MR. Stress fracture of the acetabular rim: and without femoral osteoplasty. Br J Sports Med 2012; 46: arthroscopic reduction and internal ﬁxation: a case report. J Bone 632–43. Joint Surg Am 2009; 91: 1480–6. Downloaded from https://academic.oup.com/jhps/article-abstract/5/1/66/4430316 by Ed 'DeepDyve' Gillespie user on 16 March 2018
Journal of Hip Preservation Surgery – Oxford University Press
Published: Jan 1, 2018
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