The abnormalities of femoral twist or version, whether increased anteversion or retroversion, are frequently overlooked. These skeletal aberrations are responsible for a host of hip problems such as impingement, instability and damage to the labrum and articular cartilage, often resulting in osteoarthritis if left untreated. In addition to the intrinsic hip damage, extra articular problems such as posterior hip impingement, pelvic tendonopathies, problems with gait and sitting as well as spinal decompensation are also very common. It is incumbent upon those who manage hip problems to be aware of the damage caused by femoral version abnormalities and the treatment options available.

BACKGROUND A periacetabular osteotomy (PAO) can reduce pain and improve quality of life in patients with hip dysplasia. While its utility for patients without traditional radiographic parameters for hip dysplasia has not been previously established, the PAO may help treat patients with hip instability that does not improve following single or multiple hip arthroscopic procedures, or when such procedures lead to hip instability. METHODS A single-surgeon registry of patients at a single institution was queried to identify patients with a lateral center-edge angle (LCEA) of ≥24° and a Tönnis angle of <10° who underwent PAO because of hip pain and/or instability that failed treatment with hip arthroscopy. Descriptive summary statistics were reported on patient demographics, mean change in LCEA, and patient-reported outcome measures, including the modified Harris hip score (mHHS) and the International Hip Outcome Tool-33 (iHOT-33), at a minimum of 6 months of follow-up. RESULTS Among 25 patients (mean age, 27.3 ± 6.9 years; 100% women), the mean LCEA increased from 27.2° (range, 24° to 37°) preoperatively to 39.0° ± 5.1° postoperatively (net increase, 11.8° ± 4.5°). Overall, the mean improvement in the mHHS was 11.5 ± 16.9 (preoperative, 59.4 ± 11.6; postoperative, 70.9 ± 20.6) and the mean improvement in the iHOT-33 was 23.8 ± 23.6 (preoperative, 32.2 ± 17.2; postoperative, 56.0 ± 30.0). Eighteen patients (72%) achieved a minimal clinically important improvement in mHHS (mean improvement, 17.4 ± 12.9) and iHOT-33 (mean improvement, 32.4 ± 19.1) scores. In comparison with 7 patients who did not show improvement, the 18 patients who showed improvement had significantly greater mean baseline patient-reported outcome scores. CONCLUSIONS To our knowledge, these findings provide the first report on outcomes of PAO in patients with hip pain following arthroscopy who do not meet the traditional criteria for acetabular dysplasia. Early benefits in clinical outcomes suggest a novel surgical indication for PAO as a potential salvage option for selected patients; however, longer-term studies are needed. LEVEL OF EVIDENCE Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Background: Version abnormalities of the femur can cause pain and hip joint damage due to impingement or instability. A retrospective clinical review was conducted on patients undergoing a subtrochanteric derotation osteotomy for either excessive anteversion or retroversion of the femur. Methods: A total of 55 derotation osteotomies were performed in 43 patients: 36 females and 7 males. The average age was 29 years (range, 14 to 59 years). The osteotomies were performed closed with an intramedullary saw. Fixation was performed with a variety of intramedullary nails. Twenty-nine percent of patients had a retroversion deformity (average, −9° of retroversion; range, +2° to −23°) and 71% had excessive anteversion of the femur (average, +37° of anteversion; range, +22° to +53°). The etiology was posttraumatic in 5 patients (12%), diplegic cerebral palsy in 2 patients (5%), Prader-Willi syndrome in 1 patient (2%), and idiopathic in 35 patients (81%). Forty-nine percent underwent concomitant surgery with the index femoral derotation osteotomy, including hip arthroscopy in 40%, tibial derotation osteotomy in 13%, and a periacetabular osteotomy in 5%. Tibial osteotomies were performed to correct a compensatory excessive external tibial torsion that would be exacerbated in the correction of excessive femoral anteversion. Results: No patient was lost to follow-up. Failures occurred in three hips in three patients (5%): two hip arthroplasties and one nonunion that healed after rerodding. There was one late infection treated successfully with implant removal and antibiotics with an excellent final clinical outcome. At an average follow-up of 6.5 years (range, 2 to 19.7 years), the modified Harris Hip Score improved by 29 points in the remaining 52 cases (P < 0.001, Wilcoxon signed-rank test). The results were rated as excellent in 75%, good in 23%, and fair in 2%. Subsequent surgery was required in 78% of hips, 91% of which were implant removals. Conclusions: A closed, subtrochanteric derotation osteotomy of the femur is a safe and effective procedure to treat either femoral retroversion or excessive anteversion. Excellent or good results were obtained in 93%, despite the need for subsequent implant removal in more than two-thirds of the patients.

BACKGROUND:A significant number of patients who undergo hip arthroscopy will subsequently undergo total hip arthroplasty (THA) or hip resurfacing arthroplasty (HRA), although limited evidence exists regarding effects of prior hip arthroscopy on the outcomes of these procedures. METHODS:Of 5091 patients who underwent hip arthroscopy, we identified 69 patients who underwent subsequent THA (46) or HRA (23). Patients were matched to patients with no history of hip arthroscopy. Preoperative and 2-year postoperative Hip disability and Osteoarthritis Outcome Score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Short Form-12, Lower Extremity Activity Scale score, and satisfaction surveys were compared. RESULTS:Patients who underwent THA with history of arthroscopy had lower postoperative Hip disability and Osteoarthritis Outcome Score Pain (82 ± 16 vs 93 ± 9, P = .003), Stiffness (85 ± 16 vs 93 ± 15, P = .01), Sports and Recreation (71 ± 22 vs 88 ± 18, P = .003), Quality-of-Life (65 ± 22 vs 86 ± 11, P < .0001), WOMAC Pain (86 ± 16 vs 93 ± 15, P = .03), WOMAC Stiffness (80 ± 21 vs 88 ± 17, P = .05), and Short Form-12 Physical Component Scores (48 ± 11 vs 54 ± 6, P = .008). They were less likely to be "very satisfied" after arthroplasty (71% vs 89%, P = .0008). CONCLUSION:Hip arthroscopy before hip arthroplasty is associated with slightly lower results in several patient-reported outcomes. These results are relevant when assessing patients for hip arthroscopy and when counseling prospective arthroplasty patients with history of arthroscopy.

* Computed tomography (CT) offers tremendous advantages in the evaluation of femoroacetabular impingement (FAI), as it allows precise measurements of osseous landmarks and relationships preoperatively and postoperatively. * Important femoral measurements to make on CT include the alpha angle, modified beta angle, femoral version, femoral head-neck offset, and femoral neck-shaft angle. * Key acetabular measurements to make on CT include the coronal and sagittal center-edge angles, the Tönnis angle, and the acetabular version. * Three main settings in which CT imaging is utilized for the evaluation of FAI are preoperative surgical planning using 3-dimensional modeling, the assessment of persistent hip pain after hip arthroscopy or a definitive surgical procedure, and the evaluation of patients requiring revision surgery. * Extra-articular hip impingement syndromes, including ischiofemoral impingement, subspine impingement, and trochanteric-pelvic impingement, are increasingly recognized as important causes of atypical hip pain, often with delayed diagnosis due to nonspecific presentation and inadequate clinical and imaging workup.

Arthroscopic osteochondroplasties were performed for 457 hips in 394 patients utilizing an anterior subcapsular approach without extensive release of the hip capsule to provide excellent visualization while minimizing the risks of fluid extravasation, capsular laxity and dislocation.

Dear Sir, We read with great enthusiasm our UK colleagues’ commentary: Are robots taking over orthopaedic surgery .1 In this age of cost savings and budget reductions, the push for more robotics and patient-specific instrumentation is inspiring. It reminds us of Franklin Delano Roosevelt’s response to the crushing Great Depression in the United States by instituting increased spending in the New Deal. It is unclear what will be the full embodiment of this change - will robots be driving …

Purpose: The purpose of this study was to evaluate the utility of computer-assisted 3-dimensional modeling in diagnosing and treating symptomatic hip impingement. Methods: Eight patients with symptomatic, focal cam and/or pincer impingement lesions underwent high-resolution computed tomography scans and computer-assisted, 3-dimensional modeling of the involved hip. Cam location, alpha angle, neck-shaft angle, femoral version, and acetabular version at the 12-o'clock through 3-o'clock positions were measured. The model was subsequently dynamized to define the preoperative range of motion and location of impingement with hip flexion, internal rotation, and internal rotation at 90 of hip flexion. Virtual cam and pincer osteoplasty was performed to establish normal head-neck offset and head sphericity and to eliminate focal rim impingement lesions. Range of motion and location of impingement were reassessed after resection in the defined area of impingement. Results: The cam lesion was located between the 12-o'clock and 4-o'clock positions in all cases. The mean alpha angle was 66.4 (range, 53 degrees to 80 degrees). Mean femoral version was 14.6 degrees (range, 5 degrees to 23 degrees). Mean preoperative hip flexion was 109.7 degrees (range, 87.5 degrees to 125.5 degrees), and mean internal rotation at 90 degrees of hip flexion was 16.degrees 2 (range, 1.7 degrees to 25.5 degrees). The location of impingement was unique in each case and not predictable based on radiographic measures alone. Virtual osteoplasty in the defined regions of impingement resulted in significant improvements in both hip flexion and internal rotation (P < .05). Conclusions: Computed tomography-based computer modeling can localize regions of anticipated mechanical impingement in symptomatic patients with hip pain. Computer-assisted navigation may be a valuable surgical tool to more accurately and reliably eliminate offending impingement lesions. Level of Evidence: Level IV, diagnostic study.

Background: Femoroacetabular impingement (FAI) is now recognized as the most common cause of early osteoarthritis in the nondysplastic hip. While the surgical treatment of FAI has demonstrated favorable clinical outcomes, the ability of an osteoplasty to reliably improve hip kinematics and range of motion remains unknown. Purpose: This study used computer-assisted 3-dimensional (3D) analysis to assess differences in hip range of motion before and after the arthroscopic surgical treatment of symptomatic FAI. Study Design: Case series; Level of evidence, 4. Methods: Ten patients with symptomatic, focal cam and/or pincer impingement lesions underwent high-resolution computed tomography scans and computer-assisted 3D modeling of the involved hip before and after corrective arthroscopic surgery by the senior author. Cam location, alpha angle, neck-shaft angle, femoral version, and acetabular version at 12-o'clock through 3-o'clock positions were measured. The model was subsequently dynamized to define the preoperative and postoperative range of motion and location of impingement with hip flexion, internal rotation, and internal rotation at 90 degrees of hip flexion. Statistical analysis of preoperative and postoperative hip flexion and internal rotation at 90 degrees of hip flexion was performed using paired t tests with P < .05 defined as significant. Results: The cam lesion was located between 12 o'clock and 5 o'clock in all cases. Mean preoperative alpha angle was 59.8 degrees (range, 36 degrees-76 degrees). Mean femoral version was 12.5 degrees (range, -15 degrees to 32 degrees). Mean preoperative hip flexion was 107.40 degrees +/- 11.6 degrees, and mean internal rotation at 90 degrees of hip flexion was 19.10 degrees +/- 13.0 degrees. The location of impingement was unique in each case and not predictable based on simple radiographic measures (ie, alpha angle) alone. Corrective femoral and rim osteoplasty resulted in significant improvements in both hip flexion (3.8 degrees; P = .002) and internal rotation (9.3 degrees; P = .0002). Mean postoperative alpha angle was 36.4 degrees (range, 22 degrees-46 degrees). Conclusion: Focal cam and/or rim osteoplasty can reliably improve hip kinematics and range of motion in patients with symptomatic FAI, particularly the limitation of internal rotation in a flexed position. Computed tomography-based computer modeling can localize regions of anticipated mechanical impingement in symptomatic patients. A complete osteoplasty in these defined regions, through an arthroscopic or open approach, predictably improves range of motion and may help to eliminate the recurrent mechanical collision and secondary chondral injury associated with FAI.

Background Femoroacetabular impingement (FAI) is now recognized as the most common cause of early osteoarthritis in the nondysplastic hip. While the surgical treatment of FAI has demonstrated favorable clinical outcomes, the ability of an osteoplasty to reliably improve hip kinematics and range of motion remains unknown. Purpose This study used computer-assisted 3-dimensional (3D) analysis to assess differences in hip range of motion before and after the arthroscopic surgical treatment of symptomatic FAI. Study Design Case series; Level of evidence, 4. Methods Ten patients with symptomatic, focal cam and/or pincer impingement lesions underwent high-resolution computed tomography scans and computer-assisted 3D modeling of the involved hip before and after corrective arthroscopic surgery by the senior author. Cam location, alpha angle, neck-shaft angle, femoral version, and acetabular version at 12-o'clock through 3-o'clock positions were measured. The model was subsequently dynamized to define the preoperative and postoperative range of motion and location of impingement with hip flexion, internal rotation, and internal rotation at 90° of hip flexion. Statistical analysis of preoperative and postoperative hip flexion and internal rotation at 90° of hip flexion was performed using paired t tests with P < .05 defined as significant. Results The cam lesion was located between 12 o'clock and 5 o'clock in all cases. Mean preoperative alpha angle was 59.8° (range, 36°-76°). Mean femoral version was 12.5° (range, −15° to 32°). Mean preoperative hip flexion was 107.40° ± 11.6°, and mean internal rotation at 90° of hip flexion was 19.10° ± 13.0°. The location of impingement was unique in each case and not predictable based on simple radiographic measures (ie, alpha angle) alone. Corrective femoral and rim osteoplasty resulted in significant improvements in both hip flexion (3.8°; P = .002) and internal rotation (9.3°; P = .0002). Mean postoperative alpha angle was 36.4° (range, 22°-46°). Conclusion Focal cam and/or rim osteoplasty can reliably improve hip kinematics and range of motion in patients with symptomatic FAI, particularly the limitation of internal rotation in a flexed position. Computed tomography–based computer modeling can localize regions of anticipated mechanical impingement in symptomatic patients. A complete osteoplasty in these defined regions, through an arthroscopic or open approach, predictably improves range of motion and may help to eliminate the recurrent mechanical collision and secondary chondral injury associated with FAI.

Within the discipline of sports medicine, articular cartilage injuries in the hip have received considerably less attention than other joints, largely due to the difficulty that practitioners have had with accurate assessment. Non-arthritic cartilage injuries in the hip refer to focal chondral defects on either the femoral or acetabular side of the joint. Focal chondral defects on the femoral side are relatively uncommon, however, and may result from axial loading or shear injury of the head within the socket. Subluxation events of the femoral head seen in high-energy contact sports may result in these types of focal chondral injuries. Cartilage injuries on the acetabular side are more common and typically present as localized cartilage delamination in the anterior-superior weight-bearing zone of the acetabular rim. The most common underlying condition resulting in these types of cartilage defects is femoroacetabular impingement. This chapter discusses current surgical indications and techniques appropriate for management of these injuries as well as clinical and radiographic methods to detect focal cartilage lesions in the hip joint.

This study reviews the second case in the literature involving the use of frozen osteochondral allograft to reconstruct a femoral head fracture-dislocation. The case involved significant, unreconstructable damage to the weightbearing area of the femoral head in an 18-year-old male. Clinical and diagnostic imaging follow up at 46 months revealed that despite magnetic resonance imaging and radiographic evidence of progressive arthrosis in the hip, including subchondral cystic change in the femoral head and localized cartilage loss in the acetabulum and femoral head, the patient had excellent function with no complications (Harris hip score 100, hip dysfunction and osteoarthritis outcome score 62, musculoskeletal function assesment score 22, SF-36 score 81). The use of osteochondral allograft may serve as a useful tool for the orthopaedic surgeon faced with an unreconstructable femoral head fracture-dislocation in a young patient.

Introduction: Femoroacetabular impingement (FAI) is one of the main causes of hip osteoarthritis. Femoral retroversion has been reported as a cause of FAI and it is well established that a retroverted femur produces hip pain and alterations in the external and internal rotation balance. However, no studies of femoral retroversion in patients with FAI have been reported. Furthermore, since the lack of internal rotation is a common feature in patients with FAI, it could be possible that femoral version abnormalities are present in these patients. The purpose of this study is to describe the femoral version in a group of patients with FAI and to assess its relation in the development of hip osteoarthritis. Methods: The history, x-rays and hip CT scans of 142 patients with FAI were reviewed. All patients presented persistent hip pain and were evaluated clinically between January 2006 and July 2008. We defined FAI when at least one of the following features were present: an abnormal alpha angle (>49°) measured on the elongated femoral neck x-ray, a positive cross-over sign or pro-trusio acetabuli in the AP pelvis x-ray, the presence of diminished anteversion in the femur ( We documented the type of FAI, the presence of acetabular dysplasia, coxa valga, coxa vara and the femoral version measured on the CT scan. The degree of osteoarthritis of the hip using the Tonnis classification was documented as well. Results: Two hundred and sixty-five FAI hips from 142 patients (73 females and 69 males) were analyzed. The average age was 36.7 years. The mean femoral version was 11.4 ° (−14.1° to 47°). We found 43 hips (16.6%) of the femora were retroverted and 133 hips (50%) had either diminished anteversion ( Conclusion: The presence of a retroverted femur seems to be a cofactor in the development of hip osteoarthritis in patients with FAI. The orthopedic surgeons should be aware of the high frequency of femoral retroversion when evaluating patients with hip impingement, in order to make the right diagnosis and treatment. It might be possible that this association between FAI and femoral retroversion is due to a common hip disease during skeletal maturation (i.e. SCFE) leading to two anatomical alterations at the proximal femur: reduced head-neck offset and retroverted femur.

BACKGROUND:open hip surgery is known to be a risk for heterotopic ossification (HO), and nonsteroidal anti-inflammatory drugs (NSAIDs) have been widely recognized as an effective prevention. Hip arthroscopy is gaining popularity thanks to the possibility of treating femoroacetabular impingement (FAI) with a minimally invasive technique, however little is known about its rate of postoperative HO. The aim of the present study is to evaluate HO prevalence after hip arthroscopy for FAI and its relationship with NSAID prophylaxis.MATERIALS AND METHODS:we retrospectively reviewed 300 FAI cases who have been managed with hip arthroscopy in two different hospitals from April 2006 to May 2009. All medical records and indications at discharge were analyzed, focusing on administration of NSAIDs, as well as follow-up roentgenograms with regard to presence of HO around the hip joint. The patients were divided into two groups: a treatment group of 285 hips which received NSAID prophylaxis and a control group of 15 hips which did not.RESULTS:five hips presented HO, with overall prevalence of 1.6%. All five patients with HO belonged to the control group. No HO was observed in the treatment group. Thus, HO rate turned out to be significantly higher (P < 0.001) in patients who did not receive NSAIDs after surgery.CONCLUSION:arthroscopic treatment of FAI is not exempt from potential development of HO. NSAIDs after arthroscopic FAI treatment seem to be an effective prevention.

Modularity in sleeved femoral components allows the exchange of the stem without disruption of the fixation between the sleeve and the surrounding bone at revision surgery. Failure to disengage the stem from the sleeve would represent an unnecessary compromise from the intended usefulness of the modular design. We report the results of an examination of 22 modular titanium alloy femoral components retrieved after 0.0 to 8.8 years in vivo. In 7 implants, the stem-sleeve interface could not be disengaged without cutting through the components or using mechanical force. Moderate to severe corrosion was detected in all 7 of these cases. Corrosive surface changes were observed in an additional 6 interfaces. There was no correlation with the length of time that the devices had been implanted. When only the stem is to be revised, orthopedic surgeons should be aware of difficulties in disengagement and anticipate alternative surgical procedures.

The increased risk of symptomatic progression towards osteoarthritis after chondral damage has led to the development of multiple treatment options for cartilage repair. These procedures have evolved from arthroscopic lavage and debridement, to marrow stimulation techniques, and more recently, to osteochondral autograft and allograft transplants, and autogenous chondrocyte implantation. The success of mosaicplasty procedures in the knee has led to its application to other surfaces, including the talus, tibial plateau, patella, and humeral capitellum. In this report, we present two cases of a chondral defect to the femoral head after a traumatic hip dislocation, treated with an osteochondral autograft (OATS) from the ipsilateral knee, and the inferior femoral head, respectively, combined with a surgical dislocation of the hip. At greater than 1 year and greater than 5 years of follow-up, MRI studies have demonstrated good autograft incorporation with maintenance of articular surface conformity, and both patients clinically continue to have no pain and full active range of motion of their respective hips. In our opinion, treatment of osteochondral defects in the femoral head surface using a surgical dislocation combined with an OATS procedure is a promising approach, as full exposure of the femoral head can be obtained while preserving its vasculature, thus enabling adequate restoration of the articular cartilage surface.

Introduction: The S-ROM ® modular hip system (DePuy, Warsaw, IN) has a cementless femoral component made of titanium alloy with a distally fluted and slotted stem. The stem mates with a sleeve that is implanted in the proximal femur. No reports exist in the literature of intraoperative difficulties in disengaging the sleeve-stem interface. Induced by the impossibility of intraop-eratively disconnecting the sleeve-stem interface in one patient leading to unintended revision of a well-fixed sleeve, we asked whether in vivo evidence for fretting or mechanically-assisted crevice corrosion of the mating surfaces could be found in retrieved components and whether its appearance is influenced by factors such as length of implantation. Methods: The sleeve-stem combinations were retrieved from 1998 to 2008 as part of our IRB-approved implant retrieval system. Twenty-two sleeve-stem interfaces of S-ROM ® femoral components were located in our retrieval collection. Seven sleeve-stem combinations were still mated when retrieved; 2 were disengaged by hammering the sleeve away from the stem, the remaining 5 had to be cut longitudinally with a diamond saw to disengage the sleeve from the stem. All disengaged sleeves were also cut to expose their inner surfaces. The surfaces of the taper region and the corresponding inner surfaces of the split sleeves were inspected macroscopically and assigned to the following groups: severe corrosion; moderate surface changes; and few or no evidence of surface changes. Microscopic examination was used to grade fretting and corrosion using an established subjective scale (Goldberg et al., 2002). The surface of the taper and the sleeve was divided into 12 regions each and every region was evaluated separately. The mean score of all 24 regions was calculated and opposed to the implantation time of the respective femoral component. Statistical analysis of correlation between the mean score and implantation length was performed using the Pearson product moment correlation. Additionally, the surface of the taper regions of 6 specimens underwent detailed analysis with SEM and EDAX. Results: In 3 of 22 sleeve-stem interfaces severe corrosion accounting for at least 80% of the surface area was detected. Furthermore, ten sleeve-stem interfaces showed moderate surface changes. Nine sleeve-stem interfaces showed few or no surface changes. There was no correlation between presence of corrosion and implantation length (r=0.13; p=0.56). Conclusion: In 3 of 22 retrieved sleeve-stem interfaces severe corrosion was found at the stem-sleeve interface. Though apparently not the rule, failure to disengage the stem from the sleeve undermines an important advantage of this type of modularity in total hip replacement and suggests that alternative procedures should be anticipated when planning for revision surgery of such (or a similar) modular femoral component.

Use of structural bone graft and/or reconstruction cage devices in acetabular revisions with major bone loss has the advantages of providing a stable construct at the anatomical hip center of rotation and, theoretically, reconstituting bone stock. When the structural graft supports more than 50% of the acetabular component, a reconstruction cage device spanning ilium to ischium should be used to protect the graft and provide structural stability. Recent introduction of trabecular metal cups and augments and custom triflanged acetabular components has increased the potential for biological fixation and long-term stability of revision constructs. Longer follow-up of these reconstructions is needed. Revisions with pelvic discontinuity and major bone loss have a high failure rate and require techniques either to reduce and plate the discontinuity or to distract the discontinuity to achieve long-term stability.

IntroductionArthroscopic treatment of femoro-acetabular impingement is increasing in popularity as an alternative to surgical dislocation or arthrotomy. The goal of this retrospective study was to assess the efficacy of this procedure and the effect of perioperative factors on outcome.MethodsNinety-six hips (79 patients) were evaluated at a mean of 35 months (range 24-54) after arthroscopy with femoral neck osteochondroplasty of a “cam” impingement lesion. The Tönnis osteoarthritis classification and alpha-angle were assessed on pre- and post-operative xrays. On clinical followup, patients rated their improvement, pain relief, and functional status. Statistical analysis of perioperative factors were performed using Chi-Square, T-tests and multi-variable analysis.ResultsMean age was 35 years (range 16-63). Sixteen hips underwent subsequent surgery (including eight total hip replacements). Eighty percent of patients felt they had improved from the surgery and 71% rated the pain relief as excellent or good. The alpha angle improved a mean of 27 degrees (range 11 to 67), but was not associated with outcome (p>0.45). An intra-operative finding of Grade 4 cartilage loss was correlated with less pain relief (p=0.03) and improvement (p= 0.01). The presence of a Grade 4 defect was associated with a retroverted acetabulum (p=0.004), a higher alpha angle (p=0.04), Tönnis grade 2 or 3 (p=0.001), and older age (p<0.001).ConclusionsWith the arthroscopic treatment of femoro-acetabular impingement, the presence of a grade 4 articular cartilage lesion is the most significant predictor of pain relief and clinical success. Hips with less damage at the time of surgery are more likely to have a better outcome. IntroductionArthroscopic treatment of femoro-acetabular impingement is increasing in popularity as an alternative to surgical dislocation or arthrotomy. The goal of this retrospective study was to assess the efficacy of this procedure and the effect of perioperative factors on outcome.