Os acetabuli and femoro-acetabular impingement: aetiology, incidence, treatment, and results
The purpose of this study was to investigate the pathogenesis, the incidence, and the results of arthroscopic treatment of os acetabuli (OSA) in a group of patients with diagnosis of femoro-acetabular impingement (FAI).
We retrospectively analyzed the full documentation of 294 hips in 273 patients (21 bilateral) operated for FAI through hip arthroscopy. We reviewed all radiographs and arthro-MRI in order to identify the incidence of OSA. All patients with OSA were then assessed with a modified Harris hip score (MHHS) pre-operatively and at the final follow-up.
Twenty-one patients (7.7%), 20 (95%) of them were male, were diagnosed with concomitant FAI and os acetabuli. In 21 cases, OSA was excised and FAI was treated with rim trimming, femoral osteoplasty, or both. In one case, a large OSA fragment was fixed with a 4 mm screw avoiding an acetabular uncoverage if excised. The average follow-up was 31 months (range from 6 to 69 months). The MHHS showed an improvement from a pre-operative MHHS of 57.5 (range from 39 to 82) to 95 (range from 73 to 100).
Os acetabuli is not uncommon and certainly associated with FAI and male gender. The etiology is probably microtraumatic. The arthroscopic OSA removal or fixation and concomitant FAI treatment showed very good results. Interestingly, these outcomes seem better than FAI treatment alone. Further studies with a wider number of patients and a longer follow-up are needed to confirm these results and understand the real role of OSA in this setting.
KeywordsFemoro-acetabular impingement Os acetabuli Modified Harris hip score (MHHS)
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- 2.Beck M, Kalhor M, Leunig M, Ganz R (2005) Hip morphology influences the pattern of damage to the acetabular cartilage: femoroacetabular impingement as a cause of early osteoarthritis of the hip. J Bone Joint Surg (Br) 87(7):1012–1018. https://doi.org/10.1302/0301-620X.87B7.15203 CrossRefGoogle Scholar
- 5.Zini R (2009) Artroscopia dell’anca. Argalia editore UrbinoGoogle Scholar
- 8.Freedman E (1934) Os acetabuli. J Bone Joint Surg 31:492–495Google Scholar
- 9.Pitto RP, Klaue K, Ganz R, Ceppatelli S (1995) Acetabular rim pathology secondary to congenital hip dysplasia in the adult. A radiographic study. Chir Organi Mov 80(4):361–368Google Scholar
- 11.Werner CM, Ramseier LE, Ruckstuhl T, Stromberg J, Copeland CE, Turen CH, Rufibch K, Bouaicha S (2012) Normal values of Wiberg’s lateral center-edge angle and Lequesne’s acetabular index a coxometric update. Skelet Radiol 41(10):1273–1278. https://doi.org/10.1007/s00256-012-1420-7 CrossRefGoogle Scholar
- 13.Steadman JR, Rodkey WG, Rodrigo JJ (2001) Microfracture: surgical technique and rehabilitation to treat chondral defects. Clin Orthop Relat Res 391 Suppl:S362–9Google Scholar
- 18.Larson CM, Stone RM (2011) The rarely encountered rim fracture that contributes to both femoroacetabular impingement and hip stability: a report of 2 cases of arthroscopic partial excision and internal fixation. Arthroscopy 27(7):1018–1022. https://doi.org/10.1016/j.arthro.2011.04.006 CrossRefGoogle Scholar
- 21.Gupta A, Redmond JM, Stake CE, Dunne KF, Domb BG (2015) Does primary hip arthroscopy result in improved clinical outcomes? 2-year clinical follow-up on a mixed group of 738 consecutive primary hip arthroscopies performed at a high-volume referral center. Am J Sports Med 28. https://doi.org/10.1177/0363546514562563