Arthroscopic hip procedures have increased dramatically over the last decade as equipment and techniques have improved. Patients who require hip arthroscopy for femoroacetabular impingement on occasion require surgery on the contralateral hip. Previous studies have found that younger age of presentation and lower Charlson comorbidity index have higher risk for requiring surgery on the contralateral hip but have not found correlation to anatomic variables. The purpose of this study is to evaluate the factors that predispose a patient to requiring subsequent hip arthroscopy on the contralateral hip. This is an IRB-approved, single surgeon retrospective cohort study from an academic, tertiary referral centre. A chart review was conducted on 310 primary hip arthroscopy procedures from 2009-2020. We identified 62 cases that went on to have a hip arthroscopy on the contralateral side. The bilateral hip arthroscopy cohort was compared to unilateral cohort for sex, age, BMI, pre-op alpha angle and centre edge angle measured on AP pelvis XRay, femoral torsion, traction time, skin to skin time, Tonnis grade, intra-op labral or chondral defect. A p-value <0.05 was deemed significant. Of the 62 patients that required contralateral hip arthroscopy, the average age was 32.7 compared with 37.8 in the unilateral cohort (p = 0.01) and BMI was lower in the bilateral cohort (26.2) compared to the unilateral cohort (27.6) (p=0.04). The average alpha angle was 76.3. 0. in the bilateral compared to 66. 0. in the unilateral cohort (p = 0.01). Skin to skin time was longer in cases in which a contralateral surgery was performed (106.3 mins vs 86.4 mins) (p=0.01). Interestingly, 50 male patients required contralateral hip arthroscopy compared to 12 female patients (p=0.01). No other variables were statistically significant. In conclusion, this study does re-enforce existing literature by stating that younger patients are more likely to require contralateral hip arthroscopy. This may be due to the fact that these patients require increased range of motion from the hip joint to perform activities such as sports where as older patients may not need the same amount of range of motion to perform their activities. Significantly higher alpha angles were noted in patients requiring contralateral hip arthroscopy, which has not been shown in previous literature. This helps to explain that larger CAM deformities will likely require contralateral hip arthroscopy because these patients likely impinge more during simple activities of daily living. Contralateral hip arthroscopy is also more common in male patients who typically have a larger CAM deformity. In summary, this study will help to risk stratify patients who will likely require contralateral hip arthroscopy and should be a discussion point during pre-operative counseling. That offering early subsequent or simultaneous hip arthroscopy in young male patients with large CAMs should be offered when symptoms are mild

With the growing number of individuals with asymptomatic cam-type deformities, elevated alpha angles alone do not always explain clinical signs of femoroacetabular impingement (FAI). Differences in additional anatomical parameters may affect hip joint mechanics, altering the pathomechanical process resulting in symptomatic FAI. The purpose was to examine the association between anatomical hip joint parameters and kinematics and kinetics variables, during level walking. Fifty participants (m = 46, f = 4; age = 34 ± 7 years; BMI = 26 ± 4 kg/m²) underwent CT imaging and were diagnosed as either: symptomatic (15), if they showed a cam deformity and clinical signs; asymptomatic (19), if they showed a cam deformity, but no clinical signs; or control (16), if they showed no cam deformity and no clinical signs. Each participant's CT data was measured for: axial and radial alpha angles, femoral head-neck offset, femoral neck-shaft angle, medial proximal femoral angle, femoral torsion, acetabular version, and centre-edge angle. Participants performed level walking trials, which were recorded using a ten-camera motion capture system (Vicon MX-13, Oxford, UK) and two force plates (Bertec FP4060–08, Columbus, OH, USA). Peak sagittal and frontal hip joint angles, range of motion, and moments were calculated using a custom programming script (MATLAB R2015b, Natick, MA, USA). A one-way, between groups ANOVA examined differences among kinematics and kinetics variables (α = 0.05), using statistics software (IBM SPSS v.23, Armonk, NY, USA); while a stepwise multiple regression analysis examined associations between anatomical parameters and kinematics and kinetics variables. No significant differences in kinematics were observed between groups. The symptomatic group demonstrated lower peak hip abduction moments (0.12 ± 0.08 Nm/kg) than the control group (0.22 ± 0.10 Nm/kg, p = 0.01). Sagittal hip range of motion showed a moderate, negative correlation with radial alpha angle (r = −0.33, p = 0.02), while peak hip abduction moment correlated with femoral neck-shaft angle (r = 0.36, p = 0.009) and negatively with femoral torsion (r = −0.36, p = 0.009). With peak hip abduction moment in the stepwise regression analysis, femoral torsion accounted for a variance of 13.3% (F(1, 48) = 7.38; p = 0.009), while together with femoral neck-shaft angle accounted for a total variance of 20.4% (R² change = 0.07, F(2, 47) = 6.01; p = 0.047). Although elevated radial alpha angles may have limited sagittal range of motion, the cam deformity parameters did not affect joint moments. Femoral neck-shaft angle and femoral torsion were significantly associated with peak hip abduction moment, suggesting that the insertion location of the abductor affects muscle's length and its resultant force vector. A varus neck angle, combined with severe femoral torsion, may ultimately influence muscle moment arms and hip mechanics in individuals with cam FAI

The literature indicates that femoroacetabular impingement (FAI) patients do not return to the level of controls (CTRL) following surgery. The purpose of this study was to compare hip biomechanics during stair climbing tasks in FAI patients before and two years after undergoing corrective surgery against healthy controls (CTRL). A total of 27 participants were included in this study. All participants underwent CT imaging at the local hospital, followed by three-dimensional motion analysis done at the human motion biomechanics laboratory at the local university. Participants who presented a cam deformity >50.5° in the oblique-axial or >60° in the radial planes, respectively, and who had a positive impingement test were placed in the FAI group (n=11, age=34.1±7.4 years, BMI=25.4±2.7 kg/m2). The remaining participants had no cam deformity and negative impingement test and were placed in the CTRL group (n=16, age=33.2±6.4 years, BMI=26.3±3.2 kg/m2). The CTRL group completed the biomechanics protocol once, whereas the FAI group completed the protocol twice, once prior to undergoing corrective surgery for the cam FAI, and the second time at approximately two years following surgery. At the human motion biomechanics laboratory, participants were outfitted with 45 retroreflective markers placed according to the UOMAM marker set. Participants completed five trials of stairs task on a three step instrumented stair case to measure ground reaction forces while 10 Vicon MX-13 cameras recorded the marker trajectories. Data was processed using Nexus software and divided into stair ascent and stair descent tasks. The trials were imported into custom written MatLab software to extract peak pelvis and hip kinematics and hip kinetic variables. Non-parametric Kruskal-Wallis tests were used to determine significant (p < 0.05) differences between the groups. No significant differences occurred during the stair descent task between any of the groups. During the stair ascent task, the CTRL group had significantly greater peak hip flexion angle (Pre-Op=58±7.1°, Post-Op=58.1±6.6°, CTRL=64.1±5.1°) and sagittal hip range of motion (ROM) (Pre-Op=56.7±6.7°, Post-Op=56.3±5.5°, CTRL=61.7±4.2°) than both the pre- and post-operative groups. Pre-operatively, the FAI group had significantly less peak hip adduction angle (Pre-Op=2±4.5°, Post-Op=3.4±4.4°, CTRL=5.5±3.7°) and hip frontal ROM (Pre-Op=9.9±3.4°, Post-Op=11.9±5.4°, CTRL=13.4±2.5°) compared to the CTRL group. No significant differences occurred in the kinetic variables. Our findings are in line with the Rylander and colleagues (2013) who also found that hip sagittal ROM did not improve following corrective surgery. Their study included a mix of cam and pincer-type FAI, and had a mean follow-up of approximately one year. Our cohort included only cam FAI and they had a mean follow-up of approximately two years, indicating with the extra year, the patients still did not show sagittal hip kinematics improvement. In the frontal plane, there was no significant difference between the post-op and the CTRL, indicating that the postoperative FAI reached the level of the CTRLs. This is in line with recent work that indicates a more medialized hip contact force vector following surgery, suggesting better hip stabilization

Hip joint preservation remains a preferred treatment option for hips with mechanically correctable pathologies prior to the development of significant secondary arthrosis. The pathologies most amenable to joint preservation are hip dysplasia and femoroacetabular impingement. These pathologies sometimes overlap. Untreated acetabular dysplasia of modest severity always leads to arthrosis if uncorrected. Acetabular dysplasia is best treated by periacetabular osteotomy, usually combined with arthrotomy for management of labral pathology and associated cam-impingement if present. Pre-operative variables associated with the best long-term outcomes include less secondary arthrosis, younger age, and concentric articular surfaces. The earlier PAO series show 20 year survivorship of 81% and 65% in Tonnis Grade 0 and 1 hips. Femoroacetabular impingement has become progressively recognised as perhaps the most common cause of secondary arthrosis. The etiology of impingement is multifactorial and includes both genetic factors and stresses experienced by the hip prior to cessation of growth. Cam impingement can be quantified by the alpha angle as measured on plain radiographs and radial MR sequences. Cam impingement can be treated by arthroscopic or open femoral head-neck osteochondroplasty. As with hip dysplasia, prognosis following treatment is correlated with the severity of pre-operative secondary arthrosis but unfortunately impinging hips more commonly have some degree of arthrosis pre-operatively whereas dysplastic hips can become symptomatic with instability in the absence of arthrosis. The scientific basis for the treatment of pincer impingement is less strong. Unlike cam impingement and hip dysplasia, pincer impingement pathology in the absence of coxa profunda has not been correlated with arthrosis and so rim trimming with labral refixation is probably performed more often than is clinically indicated. Overall, joint preserving surgery remains the preferred treatment for hips with mechanically correctable problems prior to the development of significant secondary arthrosis

Hip joint preservation remains a preferred treatment option for hips with mechanically correctable pathologies prior to the development of significant secondary arthrosis. The pathologies most amenable to joint preservation are hip dysplasia and femoroacetabular impingement. These pathologies sometimes overlap. Untreated acetabular dysplasia of modest severity always leads to arthrosis if uncorrected. Acetabular dysplasia is best treated by periacetabular osteotomy, usually combined with arthrotomy for management of labral pathology and associated cam-impingement if present. Preoperative variables associated with the best long-term outcomes include less secondary arthrosis, younger age, and concentric articular surfaces. Femoroacetabular impingement has become progressively recognised as perhaps the most common cause of secondary arthrosis. The etiology of impingement is multifactorial and includes both genetic factors and stresses experienced by the hip prior to cessation of growth. Cam impingement can be quantified by the alpha angle as measured on plain radiographs and radial MR sequences. Cam impingement can be treated by arthroscopic or open femoral head-neck osteochondroplasty. As with hip dysplasia, prognosis following treatment is correlated with the severity of preoperative secondary arthrosis but unfortunately impinging hips more commonly have some degree of arthrosis preop whereas dysplastic hips can become symptomic with instability in the absence of arthrosis. The scientific basis for the treatment of pincer impingement is less strong. Unlike cam impingement and hip dysplasia, pincer impingement pathology in the absence of coxa profunda has not been correlated with arthrosis and so rim trimming with labral refixation is probably performed more often than is clinically indicated. Overall, joint preserving surgery remains the preferred treatment for hips with mechanically correctible problems prior to the development of significant secondary arthrosis

Hip joint preservation remains a preferred treatment option for hips with mechanically correctable pathologies prior to the development of significant secondary arthrosis. The pathologies most amenable to joint preservation are hip dysplasia and femoroacetabular impingement. These pathologies sometimes overlap. Untreated acetabular dysplasia of modest severity, if left uncorrected, always leads to arthrosis. Acetabular dysplasia is best treated by periacetabular osteotomy, usually combined with arthrotomy for management of labral pathology and associated cam-impingement if present. Pre-operative variables associated with the best long-term outcomes include less secondary arthrosis, younger age, and concentric articular surfaces. Femoroacetabular impingement has become progressively recognised as perhaps the most common cause of secondary arthrosis. The etiology of impingement is multifactorial and includes both genetic factors and stresses experienced by the hip prior to cessation of growth. Cam impingement can be quantified by the alpha angle as measured on plain radiographs and radial MR sequences. Further, significant cam impingement is clearly associated with the development of osteoarthrosis. Treatment can be performed either by arthroscopic or open femoral head-neck osteochondroplasty. As with hip dysplasia, prognosis following treatment is correlated with the severity of preoperative secondary arthrosis but unfortunately impinging hips more commonly have some degree of arthrosis preop whereas dysplastic hips can become symptomatic with instability in the absence of arthrosis. The scientific basis for the treatment of pincer impingement is less strong. Unlike cam impingement and hip dysplasia, pincer impingement pathology in the absence of coxa profunda has not been correlated with arthrosis and so rim trimming with labral refixation is probably performed more often than is clinically indicated. Similarly, caution should be exercised when considering rim-trimming for protrusion since high central contact pressures due to an enlarged acetabular notch are not corrected by rim trimming. Overall, joint preserving surgery remains the preferred treatment for hips with mechanically correctable problems prior to the development of significant secondary arthrosis

Surgical invention to preserve the native hip joint remains a preferred treatment option for hips in young patients with mechanically correctable pathologies prior to the development of significant secondary arthrosis. The two most common pathologies most amenable to joint preservation are hip dysplasia and femoroacetabular impingement. These pathologies sometimes overlap. Untreated acetabular dysplasia of modest severity, if left uncorrected, always leads to arthrosis. Acetabular dysplasia is best treated by periacetabular osteotomy, usually combined with arthrotomy for management of labral pathology and associated cam-impingement, if present. Correction of deformities on the femoral side is now less common and reserved for only the more severe combined femoral and acetabular dysplasias or the rare isolated femoral dysplasia. Pre-operative variables associated with the best long-term outcomes include less secondary arthrosis, younger age, and concentric articular surfaces. Femoroacetabular impingement has become progressively recognised as perhaps the most common cause of secondary arthrosis. The etiology of impingement is multifactorial and includes both genetic factors and stresses experienced by the hip prior to cessation of growth. Cam impingement can be quantified by the alpha angle as measured on plain radiographs and radial MR sequences. Further, significant cam impingement is clearly associated with the development of osteoarthrosis. Treatment can be performed either by arthroscopic or open femoral head-neck osteochondroplasty. As with hip dysplasia, prognosis following treatment is correlated with the severity of pre-operative secondary arthrosis but unfortunately impinging hips more commonly have some degree of arthrosis pre-op whereas dysplastic hips can become symptomatic with the onset of instability in the absence of significant secondary arthrosis. The scientific basis for the treatment of pincer impingement is less strong. Unlike cam impingement and hip dysplasia, pincer impingement pathology in the absence of coxa profunda has not been correlated with arthrosis and so rim trimming with labral refixation is probably performed more often than is clinically indicated. Similarly, caution should be exercised when considering rim-trimming for protrusion since high central contact pressures due to an enlarged acetabular notch are not corrected by rim trimming. Overall, joint preserving surgery remains the preferred treatment for hips with mechanically correctable problems prior to the development of significant secondary arthrosis

Introduction. Bony deformities in the hip that cause femoroacetabular impingement (FAI) can be resected in order to delay the onset of osteoarthritis and improve hip range of motion. However, achieving accurate osteoplasty arthroscopically is challenging because the narrow hip joint capsule limits field of view. Recently, image-based navigation using a preoperative plan has been shown to improve the accuracy of femoral bone surfaces following arthroscopic osteoplasty for FAI. The current standard for intraoperative monitoring, 3D x-ray fluoroscopy, is accurate at the initial registration step to within 0.8±0.5mm but involves radiation. Intraoperative 3D ultrasound (US) is a promising radiation-free alternative for providing real-time visual feedback during FAI osteoplasty. The objective was to determine if intraoperative 3D US of the femoral head/neck region can be registered to a CT-based preoperative plan with comparable accuracy to fluoroscopic navigation in order to visualise progress during arthroscopic FAI osteoplasty. Methods. The experiment used a plastic femur model that had a cam deformity on the femoral head/neck. Thirty metal fiducial markers were placed on the US-accessible anterior and lateral surfaces of the femur. A CT image was acquired and reconstructed, then used to develop a preoperative plan for resection of the cam deformity. Twenty-two sets of 3D US data were then gathered from the phantom using a clinical ultrasound machine and 3D transducer while the phantom was submerged in water. US surfaces from the anterior/lateral regions of the femur were extracted using a recently proposed image processing algorithm. Fiducials in the US volume were manually registered to corresponding CT fiducials to provide a reference standard registration. The reference standard fiducial registration error (FRE) was measured as the average distance between corresponding fiducials. After fiducial-based registration, each US surface was randomly misaligned and re-registered using a coherent point-drift algorithm. The resulting surface registration error (SRE) was measured using average distance between US and CT surfaces. Finally, a plastic model of the preoperative cam deformity resection plan was 3D-printed to represent the postoperative femur. Five US scans were acquired of the postoperative model near the femoral head/neck. Each US scan was initialised for 20 trials using three reference points, and then registered using coherent point drift. Surgical outcome accuracy was reported using final surface registration error (fSRE). Results. The reference standard FRE was 0.41±0.19mm. The distance between surfaces following misalignment and re-registration for all 2200 automated registration trials was similarly small (SRE = 0.31±0.04mm) and well below the required clinical limit. Lastly, the postoperative model was accurately registered to corresponding US scans (fSRE = 0.58±0.07mm). Qualitative visualisation showed good surface matching following US to CT registration. Conclusion. Initial registration between intraoperative 3D US and preoperative CT is critical for accurate visualisation of surgical progress during FAI osteoplasty. Given spatial initialisation, the achievable registration accuracy of 3D US to CT is 0.31±0.04mm (SRE) which is well within the fluoroscopy standard, 0.8±0.5mm. The results suggest strong potential for ultrasound to guide computer-assisted arthroscopic FAI osteoplasty

Surgical management of cam-type femoroacetabular impingement (FAI) aims to preserve the native hip, restore joint function, and delay the onset of osteoarthritis. However, it is unclear how surgery affects joint mechanics and hip joint stability. The aim was to examine the contributions of each surgical stage (i.e., intact cam hip, capsulotomy, cam resection, capsular repair) towards hip joint centre of rotation and microinstability. Twelve fresh, frozen cadaveric hips (n = 12 males, age = 44 ± 9 years, BMI = 23 ± 3 kg/m2) were skeletonized to the capsule and included in this study. All hips indicated cam morphology on CT data (axial α = 63 ± 6°, radial α = 74 ± 4°) and were mounted onto a six-DOF industrial robot (TX90, Stäubli). The robot positioned each hip in four sagittal angles: 1) Extension, 2) Neutral 0°, 3) Flexion 30°, and 4) Flexion 90°, and performed internal and external hip rotations until a 5-Nm torque was reached in each direction, while recording the hip joint centre's neutral path of translation. After the (i) intact hip was tested, each hip underwent a series of surgical stages and was retested after each stage: (ii) T-capsulotomy (incised lateral iliofemoral capsular ligament), (iii) cam resection (removed morphology), and (iv) capsular repair (sutured portal incisions). Eccentricity of the hip joint centre was quantified by the microinstability index (MI = difference in rotational foci / femoral head radius). Repeated measures ANOVA and post-hoc paired t-tests compared the within-subject differences in hip joint centre and microinstability index, between the testing stages (CI = 95%, SPSS v.24, IBM). At the Extension and Neutral positions, the hip joint centre rotated concentrically after each surgical stage. At Flexion 30°, the hip joint centre shifted inferolaterally during external rotation after capsulotomy (p = 0.009), while at Flexion 90°, the hip joint centre further shifted inferolaterally during external rotation (p = 0.005) and slightly medially during internal rotation after cam resection, compared to the intact stages. Consequently, microinstability increased after the capsulotomy at Flexion 30° (MI = +0.05, p = 0.003) and substantially after cam resection at Flexion 90° (MI = +0.07, p = 0.007). Capsular repair was able to slightly restrain the rotational centre and decrease microinstability at the Flexion 30° and 90° positions (MI = −0.03 and −0.04, respectively). Hip microinstability occurred at higher amplitudes of flexion, with the cam resection providing more intracapsular volume and further lateralizing the hip joint during external rotation. Removing the cam deformity and impingement with the chondrolabral junction also medialized the hip during internal rotation, which can restore more favourable joint loading mechanics and stability. These findings support the pathomechanics of cam FAI and suggest that iatrogenic microinstability may be due to excessive motions, prior to post-operative restoration of static (capsular) and dynamic (muscle) stability. In efforts to limit microinstability, proper nonsurgical management and rehabilitation are essential, while activities that involve larger amplitudes of hip flexion and external rotation should be avoided immediately after surgery

When patients present at an early age with osteoarthritis of the hip, there is usually an underlying predisposing cause. In men, a common cause is femoroacetabular impingement (FAI). This is evident as anterior neck osteophytes, with retroversion and varus alignment of the femoral head, most likely the result of subclinical slipped capital femoral epiphysis. The resulting femoroacetabular cam impingement causes degenerative osteoarthritis (OA) of the hip, at an earlier age than primary OA. Patients present in their 40s and 50s with advanced arthritis, and are faced with the prospect of a total hip arthroplasty. Women may experience this as well, but may present with early hip arthritis as a result of subclinical dysplasia or pincer FAI more often than their male counterparts. Hip resurfacing has several advantages over traditional total hip replacement for younger patients, especially men. These include bone preservation, less dislocation, thigh pain or leg length inequality, easier return to athletics, and easy revision on the femoral side. It is indicated in young, active patients. The resurfacing procedure realigns the femoral head on the native and resurfaces the arthritic joint. Anterior neck osteoplasty is performed. Head retroversion is corrected. This restores deep flexion, and eliminates forced external rotation in flexion. Hip resurfacing can be done through either an anterior or posterior approach, although the anterior approach gives easier access to the anterior femoral neck, and preserves the blood supply to the head. This may help prevent femoral neck fractures and late head collapse

There are three major diagnoses that have been associated with early hip degeneration and subsequent hip replacement in young patients: FAI, hip dysplasia and hip osteonecrosis. I will focus mainly on the first two. Both conditions, if diagnosed early in the symptomatic patient, can be surgically treated in order to try to prevent further hip degeneration. But, what is the natural history of these disorders?. Our recent paper published this year described the natural history of hip dysplasia in a group of patients with a contralateral THA. At an average of 20 years, 70% of hips that were diagnosed at Tönnis Grade 0, had progression in degenerative changes with 23% requiring a THA at 20 years. Once the hip degeneration progressed to Tönnis 1, then 60% of hips progressed and required a THA. This natural history study demonstrates that degeneration of a dysplastic hip will occur in over 2/3 of the hips despite the limitations of activity imposed by a contralateral THA. In this same study, we were unable to detect a significant difference in progression between FAI hips and those categorised as normal. FAI damage has been commonly considered to be “motion-induced” and as such, the limitations imposed by the THA, might have limited the progression in hip damage. Needless to say, progression was seen in about half of the hips at 10 years, but very few required a THA at final follow-up. We have recently presented data on a group of young asymptomatic teenagers with FAI. At 5 years of follow-up, the group of patients with limited ROM in flexion and internal rotation, cam deformity and increased alpha angles, depicting a more severe form of disease, showed MRI evidence of progression in hip damage and worst clinical scores than a control group. This data supports our initial impressions that FAI may truly lead to irreversible hip damage. Is surgery always the option? I indicate surgery when the patient is symptomatic and has a correctable structural problem that has failed non-operative management. The data suggests that few patients improve with physical therapy, but activity modification may be an option in patients with FAI as the hip damage is mainly activity related. This may not be the case with hip dysplasia. For hip dysplasia, my current recommendations are in the form of a periacetabular osteotomy (PAO) to correct the structural problem. The procedure leads to improvement in pain as it takes care of the 4 pain generators in the dysplastic hip: the labrum, cartilage, abductors, and resultant instability. The labrum and cartilage are off-loaded with the PAO, the instability is improved by providing containment and the abductor pain is improved by improving the hip mechanics by medializing the acetabulum. I perform a hip arthroscopy prior to the PAO in the majority to treat the labrum and to perform a head neck junction osteochondroplasty, if needed. Correction of the dysplasia to a more normal hip, will improve the outcome of these hips in the long-term. For FAI, arthroscopy has become the best option for management and today is considered the gold standard. A careful review of the imaging is important prior to surgical decision making as patient selection and surgical correction is key. Poor outcomes have been seen in patients with advanced degenerative changes (joint space narrowing, femoral head damage) or in patients with incomplete correction of the deformity. Open surgical correction is an option in cases where deformity precludes an arthroscopic treatment alone

The purpose of this study was to investigate whether patients who had had excision of the Ligamentum Teres as part of a surgical hip dislocation for femoro-acetabular impingement exhibited symptoms of acute Ligamentum Teres rupture post-operatively. Recent reports in the literature suggest that injury to the Ligamentum Teres can cause instability, severe pain and inability to walk. We present the results of a postal questionnaire to 217 patients who had undergone open surgical hip dislocation for femoro-acetabular impingement where the LT was excised. This included seven patients who had undergone bilateral surgery. The questionnaire was designed to enquire about specific symptoms attributed to LT injuries in the literature; gross instability, incomplete reduction, inability to bear weight and mechanical symptoms. 161 patients responded (75%), with a total of 168 (75%) questionnaires regarding 224 hips completed. There were 104 females and 64 males. Median age was 34 and median follow-up was 52 months. All patients were found to have cam deformities, 72% (n=121) had associated labral tears. All patients were able to fully weight bear after surgery. 77% experienced no groin pain and 61% experienced no pain on exercise. 35% of patients experienced popping and locking in their operated hip and 24% had subjective feeling of their hip giving way. Oxford Hip scores and Nonarthritic Hip scores improved by 12 and 28 points respectively (n=47). Our results show that the symptoms of pain and instability described with LT pathology can be present but are by no means universal. This leads us to conclude that their symptoms may be attributed to labral pathology which is frequently noted to coexist

Introduction. Femoro-acetabular impingement (FAI) is a common source of impaired motion of the hip, often attributed to the presence of an aspherical femoral head. However, other types of femoral deformity, including posterior slip, retroversion, and neck enlargement, can also limit hip motion. This study was performed to establish whether the “cam” impinging femur has a single deformity of the head/neck junction or multiple abnormalities. Materials and Methods. Computer models of 71 femora (28 normal and 43 “cam” impinging) were prepared from CT scans. Morphologic parameters describing the dimensions of the head, neck, and medullary canal were calculated for each specimen. The anteversion angle, alpha angle of Notzli, beta angle of Beaulé, and normalized anterior heads offset were also calculated. Average dimensions were compared between the normal and impinging femora. Results. Compared to the normal controls, the impinging femora had wider necks (AP: 15.2 vs 13.3 mm, p<0.0001), larger heads (diameter: 48.3mm vs 46.0mm, p=0.032) and decreased head/neck ratios (1.60 vs 1.74, p=0.0002). However, there was no difference in neck/shaft angle (125.7° vs 126.5°, p=0.582) or anteversion angle (8.70 vs 8.44°, p=0.866). Most significantly, 53% of impinging femora also had a significant posterior slip (>2mm), compared to only 14% of normal controls. Average head displacements for the two groups were: FAI: 1.93mm vs Normals: 0.78mm (p<0.0001). Conclusions. The CAM impinging femur has many abnormalities apart from the “bump” at the head/neck junction. These femora have increased neck width and head/neck ratio, a smaller spherical bearing surface, and reduced neck offset from the medullary canal. Therefore, surgical treatment limited to localized re-contouring of the head–neck profile may fail to address significant components of the underlying abnormality

Introduction:. Cam type femoroacetabular impingement (FAI) may lead to osteoarthritis (OA)[1]. In 2D studies, an alpha angle greater than 55° was considered abnormal however limitations of 2D alpha angle measurement have led to the development of 3D methods [2–4]. Failure to completely address the bony impingement lesions during surgery has been the most common reason for unsuccessful hip arthroscopy surgery [5]. Robotic technology has facilitated more accurate surgery in comparison to the conventional means. In this study we aim to assess the potential application of robotic technology in dealing with this technically challenging procedure of cam sculpting surgery. Methods:. CT scans of three patients' hips with severe cam deformity (A, B and C models) were obtained and used to construct 3D dry bone models. A 3D surgical plan was made in custom written software. Each 3D plan was imported into the Acrobot Sculptor robot and bone resection was carried out. In total, 42 femoral models were sculpted (14/subset), thirty of which were performed by a single operator and the remaining 12 femurs were resected by two other operators. CT of the pre/post resected specimens was segmented and a 3D alpha angle and head neck ratios were measured [3–4] and compared using Mann-Whitney U test. Coefficient of variation (CV) was used to determine the degree of variation between the mean and maximum observed alpha angles for inter and intra observer repeatability. Results:. The maximal alpha angle in cam A, B and C (90.8°, 91.3° and 87.1°). There was significant reduction (p < 0.001) in maximum alpha angles post-operatively within all three models when compared to original model (Figure 1). The HNRs for cam A, B and C prior to surgery were found to be 3.2, 3.4 and 3.1 respectively that were reduced to a mean of 3.0 ± 0.1, 3.1 ± 0.1 and 3.1 ± 0.0, following resection surgery. The results of the intra and inter-observer repeatability study found good reproducibility (CV<10%) of the maximum and mean alpha angles between the 12 resected femurs. Discussion:. In this study we evaluated the use of robotic system to perform cam correction surgery by evaluating the 3D morphology of head/neck prior to and post surgery. With existing surgical options there is a potential for under or over-resection of the cam lesion, which runs the risk of the need for further surgery or rarely neck fracture and dislocation. Based on the calculated alpha angles and HNRs we have proved that we have successfully performed the surgery by avoiding under and over resection respectively. Amore accurate bony resection performed here may minimize the complications due to over and under resection and hence will decrease the burden on the health service

INTRODUCTION. Symptomatic hip disorders associated with cam deformities are routinely treated with surgery, during which the deformity is resected in an effort to restore joint range of motion, reduce pain, and protect the joint from further degeneration. This is a technically demanding procedure and the amount of correction is potentially critical to the success of the procedure: under-resection could lead to continued progression of the OA disease process in the joint, while over-resection puts the joint at risk for fracture. This study compares the accuracy of a new robotically assisted technique to a standard open technique. METHODS. Sixteen identical Sawbones models with a cam type impingement deformity were resected by a single surgeon simulating an open procedure. An ideal final resected shape was the surgical goal in all cases. 8 procedures were performed manually using a free-hand technique and 8 were performed using robotic assistance that created a 3-dimensional haptic volume defined by the desired post-operative morphology. All of 16 sawbones, including uncut one as well, were scanned by Roland LPX-600 Laser scanner with 1mm plane scanning pitch and 0.9 degree of rotary scanning. Post-resection measurements included arc of resection, volume of bone removed and resection depth and were compared to the pre-operative plan. RESULTS. The desired arc of resection was 117.7° starting at −1.8° and ending at 115.9°. Manual resection resulted in an average arc of resection error of 42.0 ± 8.5° with an average start error of −18.1 ± 5.6° and end error of 23.9 ± 9.9° compared to a robotic arc of resection error of 1.2 ± 0.7° (p<0.0001), an average start error of −1.1 ± 0.9° (p<0.0001) and end error of −0.1 ± 1.0° (p<0.0001). Over-resection occurred with every manual resection with an average volume error of 758.3 ± 477.1mm. 3. compared to an average robotic resection volume error of 31.3 ± 220.7mm. 3. (4 over- and 4 under-resected; p<0.01). CONCLUSION. Even using an approach that maximizes visualization, robotic assistance proved to be significantly more accurate and less variable than manual techniques. This is critical as the success of the surgical treatment of FAI depends on accurate and precise boney resection. The benefits of this new technique may prove even more valuable with less invasive, arthroscopic treatments that can be even more technically demanding

Introduction. Herniation pits had been considered as a normal variant, a cystic lesion formed by synovial invagination. On the contrary, it was also suggested that herniation pits were one of the diagnostic findings in femoroacetabular impingement (FAI) because of the high prevalence of herniation pits in the FAI patients. To date, the exact etiology is still unknown. The purpose of this study was to evaluate whether there is an association between the presence of herniation pits and morphological indicators of FAI based on computed tomography (CT) examination. Materials and methods. We reviewed the CT scans of 245 consecutive subjects (490 hips, age: 21–89 years) who had undergone abdominal and pelvic CT for reasons unrelated to hip symptom from September, 2010 to June, 2011. These subjects were mainly examined for abdominal disorders. We confirmed by the questionnaire survey that there were no subjects who had symptoms of hip joints. We reviewed them for the presence of herniation pits and the morphological abnormalities of the femoral head and acetabulum. Herniation pits were diagnosed when they were located at the anterosuperior femoral head-neck junction with a diameter of more than 3 mm. We measured following four signs as indicators for FAI: α angle, center edge angle (CE angle), acetabular index (AI), and acetabular version. Mann-Whitney U-test was used for statistical analysis. Results. Herniation pits were identified in 61 of the 245 subjects or, with respect to individual hips, in 85 (17%) of 490 hips. The prevalence of herniation pits in younger subjects (<60 years, 240 hips) and elderly subjects (≥60 years, 250 hips) were 16.3% and 18.4%, respectively. Among 85 hips, the mean diameter of herniation pits was 5.9 ± 2.4 mm and it was significantly larger (p<0.01) in the elderly subjects (7.1 ± 2.4 mm) than in the younger subjects (4.7 ± 1.7 mm). In terms of the α angle, there were significant differences between the group with (49.8 ± 16.6°) and without herniation pits (40.7 ± 6.7°) in the elderly subjects, whereas not significantly different among the younger subjects. Measurements of the acetabular coverage (CE angle, AI) and the acetabular version showed no significant difference between the subject with and without herniation pits. Discussion. In the present study, the prevalence of herniation pits was 17% in asymptomatic Japanese general population. The fact that the size of the herniation pits enlarge with age may suggest these cystic lesions have degenerative characteristics with no association with FAI. Although large α angles have been recognized as a predictor of cam impingement especially in young population, it was impossible to show the relationship between α angle and presence of herniation pits in young population. These results suggest that the presence of the herniation pits has little relevance to FAI diagnosis