Cam lesion femoral osteoplasty: in vitro biomechanical evaluation of iatrogenic femoral cortical notching and risk of neck fracture

Accuracy of Computer Navigation-Assisted Arthroscopic Osteochondroplasty for Cam-Type Femoroacetabular Impingement Using the Model-to-Image Registration Method

BACKGROUND

Precise osteochondroplasty is important in arthroscopic hip surgery for cam-type femoroacetabular impingement (FAI). Although computer-assisted surgery with a navigation system may enhance the accuracy of arthroscopic osteochondroplasty, few clinical studies have assessed its accuracy.

PURPOSE

To evaluate the accuracy of arthroscopic osteochondroplasty by a computed tomography (CT)-based navigation system for cam-type FAI, using 3-dimensional (3D) reconstruction with more detail compared with previous methods.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twenty patients (14 men and 6 women) who underwent navigation-assisted arthroscopic surgery for cam-type FAI were included. The preoperative 3D model of the femur was constructed from each patient's CT data, and a planned model with virtual cam resection was generated. A femoral model was reconstructed from CT data postoperatively. The 3 models for each patient were overlaid using a 3D model registration method. Then, the contours of the bone resection area of each model were compared by measuring them. To measure the deviation between planned and actual bone resections, 4 cross-sectional images of the 3 femoral models were set at one-quarter intervals from the femoral head radius. All measurements were based on clockface lines set around the femoral neck axis at 30-minute intervals. Differences between the planned and postoperative contour lines were deemed resection deviations.

RESULTS

All cam resections were performed in the anterior half of the region of interest. Therefore, only the anterior half (48 points) of the 96 points per case were analyzed. In 876 (91.3%) points of the total measurement points (960 points/20 cases), the error in resection depth was within 3 mm. Overresection was observed at 35 (3.6%) points and underresection at 49 (5.1%) points. The observed maximum deviations from the planned models were 6.3 mm overresection and -7.1 mm underresection. The alpha angles of the postoperative model at the posterior 9- to 3-o'clock position were <55° in all patients.

CONCLUSION

Navigation-assisted arthroscopic osteochondroplasty showed favorable accuracy. Underresection was more frequent than overresection on the anterosuperior side of the femur, despite assistance of the navigation system.

Femoral Neck Over-Resection After Hip Arthroscopy Treated with Vascularized Fibula Autograft: A Case Report

CASE

We describe a case of femoroacetabular impingement syndrome treated with labral repair and arthroscopic femoral osteoplasty in a 30-year-old man. The case was complicated by resection of 50% of the femoral neck resulting in high risk of an impending femoral neck fracture. The patient was treated with a vascularized fibula autograft and internal fixation.

CONCLUSION

Complications of femoral neck over-resection can threaten the viability and structural integrity of the hip joint but may successfully be treated with vascularized fibula autograft.

Top Ten Pearls for Successful Hip Arthroscopy for Femoroacetabular Impingement

Hip arthroscopy is an increasingly popular procedure used to treat femoroacetabular impingement. However, the procedure is technically challenging with a steep learning curve. To prevent complications and to optimize patient outcomes, proper patient positioning, correct portal placement, and adequate capsular closure are necessary. For central compartment procedures, creation of a minimal interportal capsulotomy, placement of traction stitches, adequate rim trimming, and balanced labral repair are recommended. For peripheral compartment procedures, adequate osteochondroplasty should be performed and assessed intraoperatively. The purpose of this technical note is to describe the senior author's top 10 pearls for a successful hip arthroscopy procedure to treat femoroacetabular impingement.

A Systematic Approach to Arthroscopic Femoroplasty With Conservative Management of the Hip Capsule

As hip arthroscopy has become increasingly used to treat femoroacetabular impingement, the importance of a complete femoroplasty to properly address cam impingement has been demonstrated. In doing so, different capsulotomy techniques have been described for gaining access to the hip joint as well as the peripheral compartment for cam resection. The periportal capsulotomy technique allows joint access while preserving the structural integrity of the iliofemoral ligament, obviating the need for capsular closure. We present a systematic approach and surgical technique for performing a complete arthroscopic femoroplasty while maintaining conservative hip capsule management through a periportal capsulotomy.

Achieving a Perfectly Spherical Femoroplasty: Pearls, Pitfalls, and Optimal Surgical Technique

Femoroacetabular impingement describes a pathologic interaction between the bony femoral head/neck junction and acetabulum. Cam-type femoroacetabular impingement results from an aspherical femoral head architecture, which increases early contact along the acetabular surface during hip range of motion. Errant arthroscopic femoroplasty recently has been discussed within the literature to describe a preventable etiology of failed hip arthroscopy, most notably cam over- and under-resection. We present an arthroscopic surgical technique for achieving the perfectly spherical femoroplasty, meant to minimize complications and improve postoperative outcomes.

Biomechanical Evaluation of the Depth of Resection During Femoral Neck Osteoplasty for Anterior Impingement Following Slipped Capital Femoral Epiphysis

BACKGROUND

Femoroacetabular impingement as a result of slipped capital femoral epiphysis (SCFE) has been treated traditionally with a proximal femoral osteotomy, but open and arthroscopic femoral osteoplasty is becoming increasingly popular. Cam lesions result from excess bone primarily at the anterolateral femoral head-neck junction. SCFEs result from posterior and inferior slippage of the femoral epiphysis, causing the metaphysis to move anteriorly. This study's purpose was to compare fourth-generation sawbones standard femurs with SCFE femurs to determine whether bone resection from the anterior metaphysis results in similar biomechanical properties.

METHODS

A custom fourth-generation composite SCFE sawbone was created with a 30-degree slip angle. Control group consisted of fourth-generation composite standard nondeformed medium femurs. The femoral neck at the head-neck junction was divided into 4 quadrants. All resections were done in the anterolateral quadrant. Twenty SCFE sawbones and 20 standard sawbones were divided into 4 subgroups based on resection depths of 0%, 10%, 30%, and 50% of the metaphysis at the head-neck junction. After resection, all proximal femurs were loaded to failure in an Instron testing machine to determine the ultimate load to failure, stiffness, and energy to failure.

RESULTS

The standard femurs were significantly stronger than the SCFE femurs (P<0.001) and the strength of the femurs decreased significantly as the resection amount increased (P<0.001). Similarly, the standard femurs withstood significantly more energy before failing than the SCFE femurs (P<0.001) and the energy to failure decreased significantly with varying resection amounts (P<0.001).

CONCLUSIONS

SCFE femurs demonstrate a significant reduction in strength and energy to failure after osteoplasty compared with nondeformed femurs in a sawbone model. Strength and energy to failure are inversely proportional to the depth of bone resection.

CLINICAL RELEVANCE

Aggressive femoral neck osteoplasty for treatment of a SCFE deformity may lead to increased risk of fracture. Further studies are necessary to determine the safe depth of resection in a clinical setting.

Mechanical Strength of the Proximal Femur After Arthroscopic Osteochondroplasty for Femoroacetabular Impingement: Finite Element Analysis and 3-Dimensional Image Analysis

PURPOSE

To examine the influence of femoral neck resection on the mechanical strength of the proximal femur in actual surgery.

METHODS

Eighteen subjects who received arthroscopic cam resection for cam-type femoroacetabular impingement (FAI) were included. Finite element analyses (FEAs) were performed to calculate changes in simulative fracture load between pre- and postoperative femur models. The finite element femur models were constructed from computed tomographic images; thus, the models represented the shape of the original femur, including the bone resection site. Three-dimensional image analysis of the bone resection site was performed to identify morphometric factors that affect strength in the postoperative femur model. Four oblique sagittal planes running perpendicular to the femoral neck axis were used as reference planes to measure the bone resection site.

RESULTS

At the transcervical reference plane, both the bone resection depth and the cross-sectional area at the resection site correlated strongly with postoperative changes in the simulated fracture load (R² = 0.6, P = .0001). However, only resection depth was significantly correlated with the simulated fracture load at the reference plane for the head-neck junction. The resected bone volume did not correlate with the postoperative changes in the simulated fracture load.

CONCLUSIONS

The results of our FEA suggest that the bone resection depth measured at the head-neck junction and transcervical reference plane correlates with fracture risk after osteochondroplasty. By contrast, bone resection at more proximal areas did not have a significant effect on the postoperative femur model strength in our FEA. The total volume of resected bone was also not significantly correlated with postoperative changes in femur model strength.

CLINICAL RELEVANCE

This biomechanical study using FEA suggest that there is a risk of femoral neck fracture after arthroscopic cam resection, particularly when the resected lesion is located distally.

In Search of the Spherical Femoroplasty: Cam Overresection Leads to Inferior Functional Scores Before and After Revision Hip Arthroscopic Surgery

BACKGROUND

Femoroplasty performed for the treatment of cam-type femoroacetabular impingement (FAI) has become a common procedure. Underresection may result in residual FAI. Conversely, overresection may disrupt the labral seal, which is responsible for chondroprotective fluid dynamics of the hip. Hypothesis/Purpose: It was hypothesized that cam overresection negatively affects hip function. The purpose was to examine the effect of the accuracy of previous femoroplasty on hips presenting for revision hip arthroscopic surgery.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Data were prospectively collected for patients presenting for revision hip arthroscopic surgery between June 2010 and August 2014. On the basis of measurements on Dunn view radiographs, cases were divided into 3 groups: overresection (OR group) in which overresection measured over 5% of the diameter of the femoral head, underresection (UR group) in which there was a residual cam lesion (alpha angle >60°), and neutral resection (neutral group). Data collection included the modified Harris Hip Score (mHHS), Nonarthritic Hip Score (NAHS), Hip Outcome Score-Sports-Specific Subscale, and visual analog scale at presentation and at a minimum 2-year follow-up after revision hip arthroscopic surgery and rates of conversion to total hip arthroplasty (THA).

RESULTS

One hundred thirty hips (120 patients) were included. Twenty hips (15.4%) were classified as the OR group, 16 (12.3%) as the UR group, and 94 (72.3%) as the neutral group. The mean follow-up was 39.6 ± 15.9 months. The mHHS and NAHS values at presentation were lower in the OR group compared with the UR group (50.2 ± 15.5 vs 64.7 ± 19.4 [ P = .033] and 48.5 ± 18.6 vs 63.0 ± 19.1 [ P = .044], respectively). The mHHS value at a minimum 2-year follow-up after revision was lower for the OR group (66.7 ± 19.8) than for the UR group (81.0 ± 14.5) ( P = .031). Conversion to THA was more common in the OR group than in the UR group (30% vs 0%, respectively; P = .024). Fifty percent of cases in the OR group, 69.9% in the neutral group, and 75% in the UR group met the minimal clinically important difference for the mHHS (Δ). The latest mHHS value reached the patient acceptable symptomatic state (PASS) in 35% of the cases in the OR group, 53.2% in the neutral group, and 75% in the UR group. Hips in the OR group had a significantly lower chance of reaching the PASS than the UR group (odds ratio, 0.1795 [95% CI, 0.0418-0.7711]; P = .0209).

CONCLUSION

Cam overresection of more than 5% of the diameter of the femoral head on the Dunn view predicts inferior clinical outcomes compared with cam underresection in this population. Furthermore, overresection predicts inferior outcomes after revision hip arthroscopic surgery and higher rates of conversion to THA.

Quantitative comparison of cortical bone thickness using correspondence-based shape modeling in patients with cam femoroacetabular impingement

The proximal femur is abnormally shaped in patients with cam-type femoroacetabular impingement (FAI). Impingement may elicit bone remodeling at the proximal femur, causing increases in cortical bone thickness. We used correspondence-based shape modeling to quantify and compare cortical thickness between cam patients and controls for the location of the cam lesion and the proximal femur. Computed tomography images were segmented for 45 controls and 28 cam-type FAI patients. The segmentations were input to a correspondence-based shape model to identify the region of the cam lesion. Median cortical thickness data over the region of the cam lesion and the proximal femur were compared between mixed-gender and gender-specific groups. Median [interquartile range] thickness was significantly greater in FAI patients than controls in the cam lesion (1.47 [0.64] vs. 1.13 [0.22] mm, respectively; p < 0.001) and proximal femur (1.28 [0.30] vs. 0.97 [0.22] mm, respectively; p < 0.001). Maximum thickness in the region of the cam lesion was more anterior and less lateral (p < 0.001) in FAI patients. Male FAI patients had increased thickness compared to male controls in the cam lesion (1.47 [0.72] vs. 1.10 [0.19] mm, respectively; p < 0.001) and proximal femur (1.25 [0.29] vs. 0.94 [0.17] mm, respectively; p < 0.001). Thickness was not significantly different between male and female controls.

CLINICAL SIGNIFICANCE

Studies of non-pathologic cadavers have provided guidelines regarding safe surgical resection depth for FAI patients. However, our results suggest impingement induces cortical thickening in cam patients, which may strengthen the proximal femur. Thus, these previously established guidelines may be too conservative. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1743-1753, 2017.

Does Removal of Subchondral Cortical Bone Provide Sufficient Resection Depth for Treatment of Cam Femoroacetabular Impingement?

BACKGROUND

Residual impingement resulting from insufficient resection of bone during the index femoroplasty is the most-common reason for revision surgery in patients with cam-type femoroacetabular impingement (FAI). Development of surgical resection guidelines therefore could reduce the number of patients with persistent pain and reduced ROM after femoroplasty.

QUESTIONS/PURPOSES

We asked whether removal of subchondral cortical bone in the region of the lesion in patients with cam FAI could restore femoral anatomy to that of screened control subjects. To evaluate this, we analyzed shape models between: (1) native cam and screened control femurs to observe the location of the cam lesion and establish baseline shape differences between groups, and (2) cam femurs with simulated resections and screened control femurs to evaluate the sufficiency of subchondral cortical bone thickness to guide resection depth.

METHODS

Three-dimensional (3-D) reconstructions of the inner and outer cortical bone boundaries of the proximal femur were generated by segmenting CT images from 45 control subjects (29 males; 15 living subjects, 30 cadavers) with normal radiographic findings and 28 nonconsecutive patients (26 males) with a diagnosis of cam FAI based on radiographic measurements and clinical examinations. Correspondence particles were placed on each femur and statistical shape modeling (SSM) was used to create mean shapes for each cohort. The geometric difference between the mean shape of the patients with cam FAI and that of the screened controls was used to define a consistent region representing the cam lesion. Subchondral cortical bone in this region was removed from the 3-D reconstructions of each cam femur to create a simulated resection. SSM was repeated to determine if the resection produced femoral anatomy that better resembled that of control subjects. Correspondence particle locations were used to generate mean femur shapes and evaluate shape differences using principal component analysis.

RESULTS

In the region of the cam lesion, the median distance between the mean native cam and control femurs was 1.8 mm (range, 1.0-2.7 mm). This difference was reduced to 0.2 mm (range, -0.2 to 0.9 mm) after resection, with some areas of overresection anteriorly and underresection superiorly. In the region of resection for each subject, the distance from each correspondence particle to the mean control shape was greater for the cam femurs than the screened control femurs (1.8 mm, [range, 1.1-2.9 mm] and 0.0 mm [range, -0.2-0.1 mm], respectively; p < 0.031). After resection, the distance was not different between the resected cam and control femurs (0.3 mm; range, -0.2-1.0; p > 0.473).

CONCLUSIONS

Removal of subchondral cortical bone in the region of resection reduced the deviation between the mean resected cam and control femurs to within a millimeter, which resulted in no difference in shape between patients with cam FAI and control subjects. Collectively, our results support the use of the subchondral cortical-cancellous bone margin as a visual intraoperative guide to limit resection depth in the correction of cam FAI.

CLINICAL RELEVANCE

Use of the subchondral cortical-cancellous bone boundary may provide a method to guide the depth of resection during arthroscopic surgery, which can be observed intraoperatively without advanced tooling, or imaging.

Complication Rates for Hip Arthroscopy Are Underestimated: A Population-Based Study

PURPOSE

To identify major and minor complication rates associated with hip arthroscopy from a payer-based national database and compare with the rates reported in the existing literature.

METHODS

Patients who underwent hip arthroscopy between 2007 and 2014 were identified using PearlDiver, a publicly available database. Rates of major and minor complications, as well as conversion to total hip arthroscopy (THA), were determined by using Current Procedural Terminology (CPT) and International Classification of Diseases, Ninth Revision (ICD-9), codes. Incidence rates of select major complications across the entire database were used as a comparison group. Statistical significance was set at P < .05.

RESULTS

Of 18 million patients screened from 2007 to 2014, a total of 2,581 hip arthroscopies were identified. The rates of major and minor complications within a 1-year postoperative period were 1.74% and 4.22%, respectively. Complications included heterotopic ossification (2.85%), bursitis (1.23%), proximal femur fracture (1.08%), deep vein thrombosis (0.79%), and hip dislocation (0.58%). The rate of conversion to THA within 1 year was 2.85%. When compared to rates in the general population, the relative risks [RRs] of requiring a THA (age <50 years, RR = 57.66, P < .001; age >50 years, RR = 22.05, P < .001), sustaining a proximal femur fracture (age <50 years, RR = 18.02, P < .001; age >50 years, RR = 2.23, P < .001), or experiencing a hip dislocation (RR 19.60, P < .001) at 1 year after hip arthroscopy were significantly higher in all age groups.

CONCLUSIONS

Higher major complication rates after hip arthroscopy were observed using a national payer-based database than previously reported in the literature, especially in regard to hip dislocations and proximal femur fractures. Rates of total hip arthroplasty were similar to prior studies, whereas the rates of revision hip arthroscopy were higher.

LEVEL OF EVIDENCE

Level IV, case series.

Complications in Hip Arthroscopy: A Systematic Review and Strategies for Prevention

The primary objective of this study was to determine the minor and major complication rate of hip arthroscopy. The secondary objective was to provide strategies for avoiding complications. A systematic review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and checklist. Therapeutic hip arthroscopy investigations that reported on adverse events or complications were included. Narrative and other systematic reviews, meta-analyses, conference abstracts or proceedings, and level V evidence studies were excluded. No follow-up minimum was imposed. The results yielded 53 studies (8189 hip arthroscopies in 8071 subjects). Most studies were level IV evidence (74%) with a mean of 2.2±2.1 years follow-up. Femoroacetabular impingement (FAI) and labral pathology were the 2 most common indications for surgery, and osteochondroplasty for FAI and labral treatment were the 2 most common procedures performed. The minor and major complication rates were 7.9% and 0.45%, respectively. Iatrogenic chondrolabral damage and temporary nerve injury were the 2 most common minor complications. Extra-articular fluid extravasation was the most common major complication encountered. Minor complications associated with hip arthroscopy are generally technical in nature and may be related to the learning curve associated with hip arthroscopy. As surgeon experience increases and patient selection improves, a corresponding decline should be observed in minor complications. Strategies to prevent complications include careful preoperative planning, appropriate surgical indications, attention to detail in the operating room, and proper postoperative rehabilitation.

Arthroscopic correction for concomitant cam impingement in a patient with idiopathic osteonecrosis of the femoral head: A case report

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It is important to accurately diagnose the status of idiopathic osteonecrosis of the femoral head and to consider another possible pathogenesis when a patient with idiopathic osteonecrosis of the femoral head has hip pain even without femoral-head collapse.

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Ignored or misdiagnosed concomitant femoroacetabular impingement in a patient with idiopathic osteonecrosis of the femoral head might leads to poor outcomes of surgical treatments such as bipolar hemiarthroplasty or osteotomies.

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In a patient with idiopathic osteonecrosis of the femoral head, it should be paid attention if concomitant femoroacetabular impingement exists or not.

A 53-year-old man presented with pain in the right hip. Radiological examination showed idiopathic osteonecrosis of the femoral head (ONFH) combined with a cam lesion. Findings on physical examination were consistent for femoroacetabular impingement. At surgery, we performed isolated arthroscopic correction for the cam lesion but did not use other treatment options such as hip arthroplasty or osteotomies for the ONFH. At the latest follow-up evaluation 3 years after surgery, findings indicted a satisfactory outcome, with a Harris hip score of 93.2 (compared with 76.4 before surgery), no joint-space narrowing, and no collapse of the femoral head. It is important to accurately diagnose the status of idiopathic ONFH and to consider another possible pathogenesis when a patient with idiopathic ONFH has hip pain even without femoral-head collapse.

Editorial Commentary: Femoroacetabular Impingement Under-resection Is the Primary Indication for Revision Arthroscopy

Complications indicating revision after hip arthroscopy generally manifest within 24 months. Femoroacetabular cam or pincher impingement deformity under-resection is the primary indication for revision arthroscopy. Revision results in decreased pain and improved function, and primary and revision hip femoroacetabular impingement arthroscopic surgeons must be mindful of femoral cam lesion over resection, which could result in iatrogenic femoral neck fracture.

Femoroacetabular impingement osteoplasty

There is an increased risk of fracture following osteoplasty of the femoral neck for cam-type femoroacetabular impingement (FAI). Resection of up to 30% of the anterolateral head–neck junction has previously been considered to be safe, however, iatrogenic fractures have been reported with resections within these limits. We re-evaluated the amount of safe resection at the anterolateral femoral head–neck junction using a biomechanically consistent model.

In total, 28 composite bones were studied in four groups: control, 10% resection, 20% resection and 30% resection. An axial load was applied to the adducted and flexed femur. Peak load, deflection at time of fracture and energy to fracture were assessed using comparison groups.

There was a marked difference in the mean peak load to fracture between the control group and the 10% resection group (p < 0.001). The control group also tolerated significantly more deflection before failure (p < 0.04). The mean peak load (p = 0.172), deflection (p = 0.547), and energy to fracture (p = 0.306) did not differ significantly between the 10%, 20%, and 30% resection groups.

Any resection of the anterolateral quadrant of the femoral head–neck junction for FAI significantly reduces the load-bearing capacity of the proximal femur. After initial resection of cortical bone, there is no further relevant loss of stability regardless of the amount of trabecular bone resected.

Based on our findings we recommend any patients who undergo anterolateral femoral head–neck junction osteoplasty should be advised to modify their post-operative routine until cortical remodelling occurs to minimise the subsequent fracture risk.

Cite this article: Bone Joint J 2015;97-B:1214–19.

Femoral Neck Fracture After Arthroscopic Femoroplasty of the Hip

Hip arthroscopy is an increasingly common procedure, particularly for the treatment of femoroacetabular impingement. Various complications have been previously reported, and the authors sought to further evaluate the safety of this procedure. This study was conducted to identify the incidence of femoral neck fracture as well as treatment and outcomes after arthroscopic femoroplasty. In April 2013, a survey was administered to 28 established hip arthroscopists regarding the breadth of their experience, including the total number of hip arthroscopies and proximal femoroplasties performed and the number of postoperative femoral neck fractures. Fracture type, patient age, patient sex, time to fracture, comorbidities, treatments, and outcomes were queried. The study identified 27,200 total arthroscopies and 14,945 proximal femoroplasties performed by the surgeons, with 11 postoperative proximal femur fractures. The incidence of proximal femur fracture after arthroscopic femoroplasty was 0.07%, based on combined data of high-volume hip arthroscopists at multiple medical centers. Mean time to fracture after arthroscopic femoroplasty was 40.5 (±26.6) days postoperatively. The male-to-female ratio was approximately 1:3 for those with fracture, and mean patient age was 52 (±13) years. More than half of the fractures were caused by violation of weight-bearing precautions. All patients had improvement in symptoms after treatment. Femoral neck fracture after arthroscopic femoroplasty is a rare complication for established hip arthroscopists. It is most common in women and patients older than 50 years. Treatment is based on the severity of the fracture, and patients have improved outcomes after treatment.

Does cam osteochondroplasty compromise proximal femur strength?

Little is known about the effect on load bearing ability of cam-type femurs following osteochondroplasty. The aim of this study was to compare the change in deformation undergone by cam-type femoral acetabular impingement femur models after resection of different volumes. Dry-bone replicas (N = 10) of two cam-type femurs (cam A and B) underwent resections of increasing volume (Surgery I, II and III) representing conservative, adequate and radical resections. Deformation under cyclic loading of 700 N for five cycles after each surgery was compared. The 360° alpha angle and the change in head to neck ratio at four equidistant points along the femoral neck were used as measures of surgical efficacy and volume resected. Intact cam A and B replicas had a maximum alpha angle of 88° and 90°, respectively, which were reduced to 55° and 54° post Surgery I. Cam A replicas showed a significant reduction (p < 0.01) in mean axial displacement after Surgery I (up to 10% reduction in neck volume) and an increase after Surgery III (~20%-40% reduction in neck volume) compared to unresected controls (p < 0.01). Surgery II (~10%-15% reduction in neck volume) produced no significant change in mean displacement (p > 0.05). Cam B models exhibited lower mean displacement after Surgery I, II and III (p < 0.01) compared to unresected controls. Conservative surgery appears to improve the axial load bearing ability of dry-bone models. Radical resections may significantly decrease the fracture-resistant properties of bone following osteochondroplasty which should be noted when planning such a procedure.

Safety measures in hip arthroscopy and their efficacy in minimizing complications: a systematic review of the evidence

PURPOSE

The purpose of this systematic review was to evaluate the literature to determine complications of hip arthroscopy, with a secondary focus on how to minimize complications and risks.

METHODS

Two independent reviewers performed a search of PubMed for articles that contained at least 1 of the following terms: complications and hip arthroscopy, hip impingement, femoral acetabular impingement and complications, or femoroacetabular impingement (FAI) and complications. The search was limited to articles published between 1999 and June 2013. An additional search was performed for articles evaluating techniques on how to minimize complications.

RESULTS

We identified 81 studies (5,535 patients; 6,277 hips). The mean age was 35.48 years, and the mean body mass index was 25.20 kg/m(2). Of the participants, 52% were male and 48% were female. The majority of studies were Level IV Evidence (63%). A total of 285 complications were reported, for an overall rate of 4.5%. There were 26 major complications (0.41%) and a 4.1% minor complication rate. The overall reoperation rate was 4.03%. A total of 94 hips underwent revision arthroscopy. Regarding open procedures, 150 patients (93%) underwent either total hip arthroplasty or a hip resurfacing procedure. The conversion rate to total hip arthroplasty or a resurfacing procedure was 2.4%.

CONCLUSIONS

Overall, primary hip arthroscopy is a successful procedure with low rates of major (0.41%) and minor (4.1%) complications. The reoperation rate was 4.03% in our review. There is admittedly a learning curve to performing hip arthroscopy, and we present a systematic review of the complications and how to minimize these complications with careful technique and planning.

LEVEL OF EVIDENCE

Level IV, systematic review of Level II to V studies.

Does the femoral cam lesion regrow after osteoplasty for femoroacetabular impingement? Two-year follow-up

BACKGROUND

There are currently no studies that have examined the recurrence of the cam lesion after femoral neck osteoplasty for femoroacetabular impingement. Although patient-reported outcome (PRO) scores at midterm follow-up have shown continued success, the maintenance of a normalized alpha angle has not been shown radiographically.

PURPOSE

To assess the radiographic recurrence of cam deformity at 2-year follow-up after adequate decompression during the index hip arthroscopic procedure and correlate the findings with PRO scores. The hypothesis was that there would be no recurrence or regrowth of the cam deformity at the 2-year postoperative time point after adequate cam decompression during hip arthroscopic surgery.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Between March 2009 and January 2011, data were prospectively collected on all patients undergoing hip arthroscopic surgery with femoral neck osteoplasty. Minimum follow-up was 2 years, with radiographic images for review.

RESULTS

A total of 47 patients met the inclusion criteria. The mean age of the participants at the start of the study was 37.18 years (range, 31.70-47.43 years). There were 28 men (59.57%) and 19 women (40.43%). The mean follow-up duration was 28.32 months (range, 24-41 months). The mean preoperative alpha angle (Dunn view) was 70° (range, 60°-97°), compared with 42.79° (range, 32°-50°) at 2 weeks postoperatively (P < .0001). The mean 2-year alpha angle was 42.72° (range, 32°-54°), which was not significantly different compared with the mean 2-week alpha angle (P = .93). Additionally, the mean femoral offset measurement was 3.7 mm (range, 0-9.9 mm) preoperatively and 7.8 mm (range, 0.3-13.9 mm) 2 weeks postoperatively (P < .0001). The mean 2-year postoperative femoral offset measurement was 8.0 mm (range, 2.4-12.8 mm), which was not significantly different compared with the mean 2-week femoral offset measurement (P = .63). All PRO scores were significantly improved at 3 months compared with preoperative scores and, except for visual analog scale score, continued to show improvement at 2-year follow-up.

CONCLUSION

There was no recurrence of cam deformity at 2 years after femoral neck osteoplasty for femoroacetabular impingement. PRO scores were improved at the 3-month and 2-year postoperative time points.