[Treatment strategies for the combination of hip dysplasia, femoroacetabular impingement and malrotation of the proximal femur : How much should be corrected?]

BACKGROUND

Hip dysplasia, FAI and femoral malrotation often occur together, resulting in mixed symptoms and severe biomechanical limitations of the hip.

OBJECTIVES

To report on the current recommendations for the best possible diagnosis and treatment strategies of combination pathologies in hip-preserving surgery.

METHODS

Review and discussion of the relevant literature with consideration of own experience in the treatment of complex combined pathomorphologies of the hip.

RESULTS

Patient history and a thorough clinical examination are key for determining the predominant pathomorphologies causing the symptoms. Standardized conventional ap pelvic and axial images of the hip are the basis for the radiological assessment of the hip, supplemented with MRI, CT and animations of the hip, depending on the case. As the pathologies influence each other functionally, a stepwise approach to treatment is recommended. The functionally most relevant pathology is treated first, followed by further corrections as needed. The primary goal is to achieve a stable hip with normal acetabular coverage, followed by an impingement-free range of motion and normalized musculoskeletal function. Care must be taken in the choice of surgical method to ensure that all pathologies can be adequately treated.

CONCLUSION

Complex, combined pathologies of the hip can be treated sufficiently with hip-preserving surgery. A thorough diagnosis is important in order to recognize the functional interaction of the different pathologies. The goal of the surgical therapy is a correctly covered, stable hip with a normal range of motion.

Improved Cartilage Quality on Delayed Gadolinium-Enhanced MRI of Hip Cartilage after Subchondral Drilling of Acetabular Cartilage Flaps in Femoroacetabular Impingement Surgery at Minimum 5-Year Follow-Up

OBJECTIVE

To assess whether subchondral drilling of acetabular cartilage flaps during femoroacetabular impingement (FAI) surgery improves (1) acetabular dGEMRIC indices and (2) morphologic magnetic resonance imaging (MRI) scores, compared with hips in which no additional treatment of cartilage lesions had been performed; and (3) whether global dGEMRIC indices and MRI scores correlate.

DESIGN

Prospective cohort study of consecutive patients with symptomatic FAI treated with open surgery between 2000 and 2007. Patients with subchondral drilling of acetabular cartilage flaps were allocated to the study group, those without drilling to the control group. All patients underwent indirect 3-T MR arthrography to assess cartilage quality by dGEMRIC indices and a semiquantitative morphologic MRI score at minimum 5 years after surgery. dGEMRIC indices and morphologic MRI scores were compared between and among groups using analysis of covariance/paired t tests.

RESULTS

No significant difference was found between the global dGEMRIC indices of the study group (449 ± 147 ms, 95% CI 432-466 ms) and the control group (428 ± 143 ms, 95% CI 416-442 ms; P = 0.235). In regions with cartilage flaps, the study group showed higher dGEMRIC indices (472 ± 160 ms, 95% CI 433-510 ms) compared with the control group (390 ± 122 ms, 95% CI 367-413 ms; P < 0.001). No significant differences were found for the morphologic MRI scores. A strong inversely linear correlation between the dGEMRIC indices and the morphologic MRI scores (r = -0.727, P < 0.001) was observed.

CONCLUSIONS

Treatment of acetabular cartilage flaps with subchondral drilling leads to better cartilage quality in regions with cartilage flaps at minimum 5 years of follow-up.

Good Outcome Scores and Low Conversion Rate to THA 10 Years After Hip Arthroscopy for the Treatment of Femoroacetabular Impingement

BACKGROUND

Arthroscopic treatment of symptomatic femoroacetabular impingement (FAI) has promising short-term to mid-term results. In addition to treating acute pain or impaired function, the goal of hip-preserving surgery is to achieve a lasting improvement of hip function and to prevent the development of osteoarthritis. Long-term results are necessary to evaluate the effectiveness of surgical treatment and to further improve results by identifying factors associated with conversion to THA.

QUESTIONS/PURPOSES

(1) How do the Merle d'Aubigné-Postel scores change from before surgery to follow-up of at least 10 years in patients undergoing hip arthroscopy for the treatment of FAI? (2) What is the cumulative 10-year survival rate of hips with the endpoints of conversion to THA or a Merle d'Aubigné-Postel score less than 15? (3) Which factors are associated with conversion to THA?

METHODS

Between 2003 and 2008, we treated 63 patients (65 hips) for symptomatic FAI with hip arthroscopy at our institution. During that period, the indications for using arthroscopy were correction of anterior cam morphology and anterolateral rim trimming with debridement or reattachment of the labrum. We excluded patients who were younger than 16 years and those who had previous trauma or surgery of the hip. Based on that, 60 patients (62 hips) were eligible. A further 17% (10 of 60) of patients were excluded because the treatment was purely symptomatic without treatment of cam- and/or pincer-type morphology. Of the 50 patients (52 hips) included in the study, 2% (1) of patients were lost before the minimum study follow-up of 10 years, leaving 49 patients (51 hips) for analysis. The median (range) follow-up was 11 years (10 to 17). The median age at surgery was 33 years (16 to 63). Ninety percent (45 of 50) of patients were women. Of the 52 hips, 75% (39 of 52) underwent cam resection (femoral offset correction), 8% (4 of 52) underwent acetabular rim trimming, and 17% (9 of 52) had both procedures. Additionally, in 35% (18 of 52) of hips the labrum was debrided, in 31% (16 of 52) it was resected, and in 10% (5 of 52) of hips the labrum was reattached. The primary clinical outcome measurements were conversion to THA and the Merle d'Aubigné-Postel score. Kaplan-Meier survivorship and Cox regression analyses were performed with endpoints being conversion to THA or Merle d'Aubigné-Postel score less than 15 points.

RESULTS

The clinical result at 10 years of follow-up was good. The median improvement of the Merle d'Aubigné-Postel score was 3 points (interquartile range 2 to 4), to a median score at last follow-up of 17 points (range 10 to 18). The cumulative 10-year survival rate was 92% (95% CI 85% to 99%) with the endpoints of conversion to THA or Merle d'Aubigné-Postel score less than 15. Factors associated with conversion to THA were each year of advancing age at the time of surgery (hazard ratio 1.1 [95% CI 1.0 to 1.3]; p = 0.01) and preoperative Tönnis Grade 1 compared with Tönnis Grade 0 (no sign of arthritis; HR 17 [95% CI 1.8 to 166]; p = 0.01).

CONCLUSION

In this series, more than 90% of patients retained their native hips and reported good patient-reported outcome scores at least 10 years after arthroscopic treatment of symptomatic FAI. Younger patients fared better in this series, as did hips without signs of osteoarthritis. Future studies with prospective comparisons of treatment groups are needed to determine how best to treat complex impingement morphologies.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Subchondral drilling for chondral flaps reduces the risk of total hip arthroplasty in femoroacetabular impingement surgery at minimum five years follow-up

INTRODUCTION:

The best treatment of acetabular chondral flaps during surgery for femoroacetabular impingement (FAI) is unknown. We asked if subchondral drilling improves clinical and radiographic outcome and if there are factors predicting failure.

METHODS:

We treated 79 patients with symptomatic FAI and acetabular chondral flaps with surgical hip dislocation between January 2000 and December 2007. Exclusion of all patients with previous hip pathology or trauma resulted in 62 patients (80 hips). The chondral flap was slightly debrided in 43 patients/51 hips (control group). In 28 patients/29 hips (study group), additional osseous drilling was performed. 4 patients (5 hips, 6%) were lost to follow-up. Mean follow-up was 9 years (5-13 years). The groups did not differ in demographic data, radiographic parameters or follow-up. Clinical outcome was assessed with the Merle d'Aubigné score, modified Harris Hip Score and University of California Los Angeles activity score and progression of osteoarthritis with the Tönnis grade.

RESULTS:

No patient underwent conversion to total hip arthroplasty (THA) in the drilling group compared to 7 patients (8 hips, 16%) in the control group ( p = 0.005); in the remaining hips, clinical scores and progression of Tönnis grade did not differ. Increased acetabular coverage, age and body mass index were univariate predictive factors for conversion to THA. No drilling was as an independent predictive factor for conversion to THA (hazard ratio 58.07, p = 0.009).

CONCLUSION:

Subchondral drilling under acetabular chondral flaps during surgical treatment of FAI is an effective procedure to reduce the rate of conversion to THA.

Influence of evolution on cam deformity and its impact on biomechanics of the human hip joint

Anatomy and biomechanics of the human hip joint are a consequence of the evolution of permanent bipedal gait. Habitat and behaviour have an impact on hip morphology and significant differences are present even within the same biological family. The forces acting upon the hip joint are mainly a function of gravitation and strength of the muscles. Acetabular and femoral anatomy ensure an inherently stable hip with a wide range of motion. The femoral head in first human ancestors with upright gait was spherical (coxa rotunda). Coxa rotunda is also seen in close human relatives (great apes) and remains the predominant anatomy of present-day humans. High impact sport during adolescence with open physis however can activate an underlying genetic predisposition for reinforcement of the femoral neck, causing an epiphyseal extension and the formation of an osseous asphericity at the antero-superior femoral neck (cam deformity). The morphology of cam deformity is similar to the aspherical hips of quadrupeds (coxa recta), with the difference that in quadrupeds the asphericity is posterior. It has been postulated that this is due to the fact that humans bear weight on the extended leg, while quadrupeds bear weight at 90-100° flexion. The asphericity alters the biomechanical properties of the joint and as it is forced into the acetabulum leading to secondary cartilage damage. It is considered a risk factor for later development of osteoarthritis of the hip. Clinically this presents as reduced range of motion, which can be an indicator for the structural deformity of the hip. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 9999:XX-XX, 2018.

Biologische Rekonstruktion lokalisiert vollschichtiger Knorpelschäden des Hüftgelenks: Empfehlungen der Arbeitsgemeinschaft „Klinische Geweberegeneration“ der DGOU und des Hüftkomitees der AGA

Hintergrund Symptomatisch präarthrotische Deformitäten wie das femoroazetabuläre Impingement (FAI) oder die Hüftdysplasie führen häufig zu lokalisierten Knorpeldefekten und nachfolgend zur Entstehung einer Koxarthrose. In der vorliegenden Arbeit werden die derzeitigen Methoden und Erkenntnisse zur Diagnose und operativen Behandlung von Knorpelläsionen dargestellt, um hieraus geeignete Therapieempfehlungen für das Hüftgelenk abzuleiten.

Material und Methoden Übersichtsarbeit zur Ätiologie und Therapie von Knorpelschäden am Hüftgelenk unter Berücksichtigung der aktuellen Literatur mit Darstellung der Studienlage und der Diskussion von Vor- und Nachteilen verschiedener operativer Verfahren zum Gelenkerhalt.

Ergebnisse In den meisten der bisher publizierten Studien zur operativen Behandlung von Knorpelschäden des Hüftgelenks wurden Defekte behandelt, die am Azetabulum durch ein FAI vom Cam-Typ ausgelöst werden. Ihre Entstehung kann durch rechtzeitige Beseitigung der pathologisch relevanten Deformitäten verhindert werden. Für die Therapie bereits bestehender vollschichtiger Knorpelläsionen werden derzeit fast ausschließlich knochenmarkstimulierende Techniken und die matrixgekoppelte autologe Knorpelzelltransplantation (MACT) eingesetzt. Für die Hüfte existieren zu diesen Verfahren bisher nur Studien auf geringem Evidenzniveau, was vor allem in der noch jungen Historie der Knorpelchirurgie in diesem Gelenk begründet ist. Allerdings ist schon jetzt zu erkennen, dass sich einige Erfahrungen mit den genannten Methoden vom Knie auf die Hüfte übertragen lassen.

Schlussfolgerung Bei umschriebenen und vollschichtigen Knorpelschäden ab 1,5 – 2 cm2 stellt die MACT das zu bevorzugende Therapieverfahren dar, sofern keine wesentliche Gelenkdegeneration besteht. Ähnlich wie im Knie kann keine gesicherte obere Altersgrenze für einen gelenkerhaltenden Eingriff oder eine MACT im Hüftgelenk festgelegt werden, da das numerische nicht zwangsläufig mit dem biologischen Patientenalter bzw. Gelenkzustand korreliert. Wie für andere Gelenke auch, sind Langzeitbeobachtungen und die Durchführung prospektiv randomisierter Studien anzuraten.

What Are the Risk Factors for Revision Surgery After Hip Arthroscopy for Femoroacetabular Impingement at 7-year Followup?

BACKGROUND

In recent years, surgical treatment of symptomatic femoroacetabular impingement (FAI) has been increasingly performed using arthroscopy. Bony pathomorphologies and damage to the labrum as well as cartilage defects can be addressed with comparable results to open surgery with overall less surgery-related complications. Despite the increasing importance of hip arthroscopy, however, reports on midterm clinical and radiographic outcomes and comparison to open surgical hip dislocation are scarce.

QUESTIONS/PURPOSES

(1) What are the clinical and radiographic outcomes at a mean 7-year followup; (2) what is the cumulative 7-year survivorship, using the endpoints of THA, progression of osteoarthritis according to Tönnis, or poor clinical outcome with a Merle d'Aubigné score of less than 15 points, of hips with symptomatic FAI treated arthroscopically; and (3) what factors were associated with revision surgery?

METHODS

Between 2003 and 2008 we performed a total of 62 arthroscopic procedures (60 patients) for FAI. For the same indication, we also performed 571 surgical hip dislocations during that time. Standardized treatment was femoral offset correction, acetabular rim trimming, or both and treatment of labral or chondral defects. An arthroscopic approach was generally used if the pathomorphology was located in the anterosuperior quadrant of the hip and was gradually used for more complex cases. We excluded 10 hips (10 patients) in which the standardized treatment was not achieved and no offset correction or acetabular rim trimming was performed. Of the remaining 52 hips (50 patients), 39 hips underwent isolated femoral offset correction, four hips isolated acetabular rim trimming, and nine hips both procedures. At a mean followup of 7 years (range, 5-11 years), the Merle d'Aubigné clinical score was obtained and plain radiographs were examined (Tönnis grade, heterotopic ossification, lateral center-edge [LCE] angle, acetabular index [AI], extrusion index, alpha angle, and pistol grip deformity). Cumulative survivorship was calculated according to Kaplan-Meier using conversion to THA, progression of osteoarthritis (one or more Tönnis grades), or poor clinical outcome (Merle d'Aubigné score < 15 points) as endpoints. Cox regression analysis was used to identify univariate factors associated with revision surgery.

RESULTS

At last followup we detected a significant but possibly not clinically relevant increase in Merle d'Aubigné scores from preoperative levels to latest followup (14 ± 1 versus 16 ± 2, mean difference 2 points with a 95% confidence interval [95% CI] -3 to 7, p < 0.001). Six hips showed progression of osteoarthritis. Cumulative survivorship (hips free from conversion to THA, progression of osteoarthritis, or poor clinical outcome) of hips treated with hip arthroscopy for FAI at a mean followup of 7 years was 81% (95% CI, 68%-95%). Two patients (two hips, 4%) underwent THA at 7 and 9 years, respectively. An increased preoperative acetabular coverage (LCE angle, AI), increased offset in the superior portion of the femoral neck (pistol grip deformity), and a remaining pistol grip deformity postoperatively were associated with revision surgery. Any treatment of the labrum did not influence the outcome. Factors associated with failure could not be identified.

CONCLUSIONS

In this series of patients with arthroscopic treatment of symptomatic FAI, hip arthroscopy resulted in an intact hip without progression of osteoarthritis and with a Merle d'Aubigné score of ≥ 15 points in 81% of patients at 7-year followup. Increased acetabular coverage and femoral pistol grip deformity were risk factors for revision surgery.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Intraoperative Evaluation of Acetabular Morphology in Hip Arthroscopy Comparing Standard Radiography Versus Fluoroscopy: A Cadaver Study

PURPOSE

To compare quantitative measurements of acetabular morphology obtained using intraoperative fluoroscopy, to standardized anteroposterior (AP) pelvis radiographs.

METHODS

Ten dried human pelvis specimens (20 hips) were imaged using hip-centered fluoroscopy and standardized AP pelvis radiographs. Each hip was evaluated for acetabular version and coverage, including lateral center edge (LCE) angle, acetabular index (AI), total anterior and posterior coverage, and crossover sign.

RESULTS

No statistically significant differences existed between the mean LCE angle (fluoroscopy 36.5° ± 8.3° v plain films 36.1° ± 7.9°, P = .59), acetabular index (0.6° ± 8.6° v 0.2° ± 7.1°, P = .61), ACM angle (44.0° ± 2.6° v 44.1° ± 3.8°, P = .89), Sharp's angle (31.8° ± 5.7° v 32.4° ± 3.9°, P = .44), and the total femoral coverage (80.9% ± 6.4% v 80.7% ± 7.5%, P = .83). Conversely, total anterior coverage (30.7% ± 8.5% v 33.3% ± 8.2%, P < .0001) appeared significantly decreased and the total posterior coverage (54.1% ± 6.9% v 49.1% ± 7.8%, P < .0001) appeared significantly increased in fluoroscopy compared with plain film radiographs. Fluoroscopy also failed to identify the presence of a crossover sign in 30% and underestimated the retroversion index (9% ± 16%, v 13% ± 16%, P = .016).

CONCLUSIONS

The values for the LCE angle and AI determined by hip-centered fluoroscopy did not differ from those obtained by standardized AP plain film radiography. However, fluoroscopy leads to a more anteverted projection of the acetabulum with significantly decreased total anterior coverage, significantly increased total posterior coverage, and underestimated signs of retroversion compared with standardized AP pelvis radiography.

CLINICAL RELEVANCE

This study shows reliable LCE and AI angles but significant differences in the projected anteversion of the acetabulum between standardized AP pelvis radiography and hip-centered fluoroscopy.

Functional recovery following primary ACL repair with dynamic intraligamentary stabilization

BACKGROUND

Recently, a new technique, dynamic intraligamentary stabilization (DIS) was introduced for the acute repair of ACL ruptures. The purpose of this study was to report the functional recovery for patients undergoing acute anterior cruciate ligament (ACL) repair alongside DIS.

METHODS

Forty five patients sustaining acute ACL rupture and treated with DIS repair were retrospectively evaluated. Limb symmetry index of the hop test as well as knee function by means of range of motion, knee swelling, pain and maximum strength were evaluated. Following completion of the rehabilitation program, the difference in anterior-posterior translation (Δ-AP Translation), IKDC, Tegner score (TAS) was additionally analyzed.

RESULTS

Forty five (13 females, 32 males) patients were included in the study. Mean age was 26years (range 18 to 54years). Median time to successfully complete hop test was 22.0weeks (range 11 to 32weeks) postoperatively. Median limb symmetry index 91.6%±8.3%. Median delta anterior-posterior translation compared to the healthy side was plus 0.0mm±1.6mm. Median IKDC was 89.5±6.5. Mean Tegner score (TAS) at 12months of follow-up was seven (range four to nine). Three patients suffered a rerupture during the first 12 postoperative months.

CONCLUSIONS

DIS technique with proper rehabilitation following acute ACL rupture provides successful functional recovery and low rerupture rate at one-year follow-up.

Anteverting Periacetabular Osteotomy for Acetabular Retroversion

Introduction

The periacetabular osteotomy procedure reorients a retroverted acetabulum into a more anatomically appropriate position.

Step 1: Evaluation of Acetabular Retroversion

Evaluate acetabular retroversion on the basis of a combination of radiographic signs.

Step 2: Patient Positioning and Skin Incision

After draping and sterile preparation with the patient in a supine position, make an incision following the skin lines of the inguinal fold.

Step 3: Exposure of the Deep Muscle Layers and the Pelvic Brim

Detach the abdominal wall muscles from the anterior iliac crest and detach the sartorius muscle and the inguinal ligament to expose the iliac fossa and the pelvic brim.

Step 4: Surgical Dissection for Preparation of the Ischial Osteotomy

Detach the iliocapsularis muscle and mobilize it medially to allow access to the infra-articular space and palpation of the ischial bone.

Step 5: Incomplete, Partial Ischial Osteotomy

Introduce a curved chisel with a crescent-shaped tip into the infra-articular space in order to perform the osteotomy of the ischial bone.

Step 6: Osteotomy of the Superior Pubic Ramus

Place subperiosteal blunt retractors around the superior pubic ramus to ensure safe and complete pubic bone osteotomy.

Step 7: Supra-Acetabular and Retroacetabular Osteotomy

Start the supra-acetabular horizontal osteotomy at the anterior superior iliac spine and end it 2 cm lateral to the pelvic brim, where the osteotomy is angled 100° distally.

Step 8: Mobilization of the Acetabular Fragment

With the help of a spreader and a 4.5-mm threaded Schanz pin, free and mobilize the acetabular fragment.

Step 9: Reorientation of the Acetabular Fragment

Perform internal rotation of the acetabular fragment with the help of the threaded Schanz pin.

Step 10: Improvement of Anterior Head-Neck Offset (Femoral Neck Osteoplasty)

Anterior capsulotomy and improvement of anterior head-neck offset is recommended when internal rotation is <30°.

Step 11: Anteroposterior Pelvic Radiograph Following Periacetabular Osteotomy

Ideally, a postoperative radiograph should show negative crossover and posterior wall signs while the ischial spine sign typically remains positive.

Results

The long-term results of the periacetabular osteotomy in a series of twenty-two patients (twenty-nine hips) with symptomatic acetabular retroversion were evaluated after a mean duration of follow-up of eleven years (range, nine to twelve years).

Indications

Contraindications

Pitfalls & Challenges

Periacetabular osteotomy: a review of swiss experience

Symptomatic dysplasia of the hip and acetabular retroversion are possible causes of osteoarthritis in the young adult. Surgical management with reorientation of the acetabulum allows causal therapy of the deformity and preservation of the native hip joint. The Ganz' periacetabular osteotomy permits a free 3-dimensional reorientation of the acetabulum and respects the blood supply of the acetabular fragment. The posterior column remains intact with a stable fixation of the acetabular fragment and a preserved shape of the true pelvis. There is a significant learning curve with severe complications in up to 30 % of cases. Good results can be expected in the long-term follow-up if performed with correct indication at young age in hips with preserved joint cartilage and proper reorientation of the acetabular fragment. Overall survivorship is superior to the natural course of hip dysplasia with a preserved hip joint in 61 % after 20 years.

Anteverting periacetabular osteotomy for symptomatic acetabular retroversion: results at ten years

BACKGROUND

Acetabular retroversion is associated with pincer-type femoroacetabular impingement and can lead to hip osteoarthritis. We report the ten-year results of a previously described patient cohort that had corrective periacetabular osteotomy for the treatment of symptomatic acetabular retroversion.

METHODS

Clinical and radiographic parameters were assessed preoperatively and at two and ten years postoperatively. A Kaplan-Meier survivorship analysis of the twenty-two patients (twenty-nine hips) with a mean follow-up (and standard deviation) of 11 ± 1 years (range, nine to twelve years) was performed. In addition, a univariate Cox regression analysis was done with conversion to total hip arthroplasty as the primary end point and progression of the osteoarthritis, a fair or poor result according to the Merle d'Aubigné score, or the need for revision surgery as the secondary end points.

RESULTS

The mean Merle d'Aubigné score improved significantly from 14 ± 1.4 points (range, 12 to 17 points) preoperatively to 16.9 ± 0.9 points (range, 15 to 18 points) at ten years (p < 0.001). There were also significant improvements with regard to hip flexion (p = 0.003), internal rotation (p = 0.003), and adduction (p = 0.002) compared with the preoperative status. No significant increase of the mean Tönnis osteoarthritis score was seen at ten years (p = 0.06). The cumulative ten-year survivorship, with conversion to a total hip arthroplasty as the primary end point, was 100%. The cumulative ten-year survivorship in achievement of one of the secondary end points was 71% (95% confidence interval, 54% to 88%). Predictors for poor outcome were the lack of femoral offset creation and overcorrection of the acetabular version resulting in excessive anteversion.

CONCLUSIONS

Anteverting periacetabular osteotomy for acetabular retroversion leads to favorable long-term results with preservation of the native hip at a mean of ten years. Overcorrection resulting in excessive anteversion of the hip and omitting concomitant offset creation of the femoral head-neck junction are associated with an unfavorable outcome.

In vitro temperature evaluation during cement augmentation of proximal humerus plate screw tips

BACKGROUND

The treatment of proximal humerus fractures in patients with poor bone quality remains a challenge in trauma surgery. Augmentation with polymethylmethacrylate (PMMA) cement is a possible method to strengthen the implant anchorage in osteoporotic bone and to avoid loss of reduction and reduce the cut-out risk. The polymerisation of PMMA during cement setting leads, however, to an exothermic reaction and the development of supraphysiological temperatures may harm the bone and cartilage. This study addresses the issue of heat development during augmentation of subchondrally placed proximal humerus plate screws with PMMA and the possible risk of bone and cartilage necrosis and apoptosis.

METHODS

Seven fresh frozen humeri from geriatric female donors were instrumented with the proximal humerus interlocking system (PHILOS) plate and placed in a 37°C water bath. Thereafter, four proximal perforated screws were augmented with 0.5 ml PMMA each. During augmentation, the temperatures in the subchondral bone and on the articular surface were recorded with K-type thermocouples. The measured temperatures were compared to threshold values for necrosis and apoptosis of bone and cartilage reported in the literature.

RESULTS

The heat development was highest around the augmented tips of the perforated screws and diminished with growing distance from the cement cloud. The highest temperature recorded in the subchondral bone reached 43.5°C and the longest exposure time above 42°C was 86s. The highest temperature measured on the articular surface amounted to 38.6°C and the longest exposure time above 38°C was 5 min and 32s.

CONCLUSION

The study shows that augmentation of the proximal screws of the PHILOS plate with PMMA leads to a locally limited development of supraphysiological temperatures in the cement cloud and closely around it. The critical threshold values for necrosis and apoptosis of cartilage and subchondral bone reported in the literature, however, are not reached. In order to avoid cement extravasation, special care should be taken in detecting perforations or intra-articular cracks in the humeral head.

[Joint preserving surgery of the adult hip: pelvic osteotomies]

Deformity and malposition of the acetabulum can occur during the development of the hip. Developmental hip dysplasia and acetabular retroversion are possible causes of osteoarthritis in the young adult. Surgical management with reorientation of the acetabulum allows causal therapy of the deformity and preservation of the native hip joint. Established techniques are the Bernese periacetabular osteotomy (PAO) and the Tönnis and Kalchschmidt triple osteotomy of the pelvis. Both techniques permit three-dimensional correction of the position of the acetabulum. Advantages and disadvantages of each technique must be considered and are summarized in the present paper. If performed early (osteoarthritis grade Tönnis 0 and 1) with correct indication and proper technique, good results can be expected.

Arthroscopic versus open cam resection in the treatment of femoroacetabular impingement

PURPOSE

The purpose of this study was to evaluate if osseous correction of the femoral neck achieved arthroscopically is comparable to that achieved by surgical dislocation.

METHODS

We retrospectively analyzed all patients who were treated with hip arthroscopy or surgical dislocation for cam or mixed type femoroacetabular impingement (FAI) in our institution between 2006 and 2009. Inclusion criteria were complete clinical and radiologic documentation with standardized radiographs. Group 1 consisted of 66 patients (49 female patients, mean age 33.8 years) treated with hip arthroscopy. Group 2 consisted of 135 patients (91 male patients, mean age 31.2 years) treated with surgical hip dislocation. We compared the preoperative and postoperative alpha and gamma angles, as well as the triangular index. Mean follow-up was 16.7 months (range, 2 to 79 months).

RESULTS

In group 1, the mean alpha angle improved from 60.7° preoperatively to 47.8° postoperatively (P < .001) and the mean gamma angle improved from 47.3° to 44.5° (P < .001). Over time, the preoperative mean alpha angle increased from 56.3° in 2006 to 67.5° in 2009, whereas the postoperative mean alpha angle decreased from 51.2° in 2006 to 47.5° in 2009. In group 2, the mean alpha angle improved from 75.3° preoperatively to 44.8° postoperatively (P < .001), and the mean gamma angle improved from 65.1° to 52.2° (P < .001). Arthroscopic revision of intra-articular adhesions was performed in 4 patients (6.1%) in group 1 and 16 patients (12%) in group 2. Three patients (2.2%) in group 2 underwent revision for nonunion of the greater trochanter.

CONCLUSIONS

Osseous correction of cam-type FAI with hip arthroscopy is comparable to the correction achieved by surgical hip dislocation. There is a significant learning curve for hip arthroscopy, with postoperative osseous correction showing improved results with increasing surgical experience.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

The acetabular wall index for assessing anteroposterior femoral head coverage in symptomatic patients

BACKGROUND

Understanding acetabular pathomorphology is necessary to correctly treat patients with hip complaints. Existing radiographic parameters classify acetabular coverage as deficient, normal, or excessive but fail to quantify contributions of anterior and posterior wall coverage. A simple, reproducible, and valid measurement of anterior and posterior wall coverage in patients with hip pain would be a clinically useful tool.

QUESTIONS/PURPOSES

We (1) introduce the anterior wall index (AWI) and posterior wall index (PWI), (2) report the intra- and interobserver reliability of these measurements, and (3) validate these measurements against an established computer model.

METHODS

We retrospectively reviewed 87 hips (63 patients) with symptomatic hip disease. A validated computer model was used to determine total anterior and posterior acetabular coverage (TAC and TPC) on an AP pelvis radiograph. Two independent observers measured the AWI and PWI on each film, and the intraclass correlation coefficient (ICC) was calculated. Pearson correlation was used to determine the strength of linear dependence between our measurements and the computer model.

RESULTS

Intra- and interobserver ICCs were 0.94 and 0.99 for the AWI and 0.81 and 0.97 for the PWI. For validation against the computer model, Pearson r values were 0.837 (AWI versus TAC) and 0.895 (PWI versus TPC). Mean AWI and PWI were 0.28 and 0.81 for dysplastic hips, 0.41 and 0.91 for normal hips, 0.61 and 1.15 for hips with a deep acetabulum.

CONCLUSIONS

Our data suggest these measures will be helpful in evaluating anterior and posterior coverage before and after surgery but need to be evaluated in asymptomatic individuals without hip abnormalities to establish normal ranges.

LEVEL OF EVIDENCE

Level III, diagnostic study. See Instructions for Authors for a complete description of levels of evidence.

Pelvic morphology differs in rotation and obliquity between developmental dysplasia of the hip and retroversion

BACKGROUND

Developmental dysplasia of the hip (DDH) and acetabular retroversion represent distinct acetabular pathomorphologies. Both are associated with alterations in pelvic morphology. In cases where direct radiographic assessment of the acetabulum is difficult or impossible or in mixed cases of DDH and retroversion, additional indirect pelvimetric parameters would help identify the major underlying structural abnormality.

QUESTIONS/PURPOSES

We asked: How does DDH and retroversion differ with respect to rotation and coronal obliquity as measured by the pelvic width index, anterior inferior iliac spine (AIIS) sign, ilioischial angle, and obturator index? And what is the predictive value of each variable in detecting acetabular retroversion?

METHODS

We reviewed AP pelvis radiographs for 51 dysplastic and 51 retroverted hips. Dysplasia was diagnosed based on a lateral center-edge angle of less than 20° and an acetabular index of greater than 14°. Retroversion was diagnosed based on a lateral center-edge angle of greater than 25° and concomitant presence of the crossover/ischial spine/posterior wall signs. We calculated sensitivity, specificity, and area under the receiver operating characteristic (ROC) curve for each variable used to diagnose acetabular retroversion.

RESULTS

We found a lower pelvic width index, higher prevalence of the AIIS sign, higher ilioischial angle, and lower obturator index in acetabular retroversion. The entire innominate bone is internally rotated in DDH and externally rotated in retroversion. The areas under the ROC curve were 0.969 (pelvic width index), 0.776 (AIIS sign), 0.971 (ilioischial angle), and 0.925 (obturator index).

CONCLUSIONS

Pelvic morphology is associated with acetabular pathomorphology. Our measurements, except the AIIS sign, are indirect indicators of acetabular retroversion. The data suggest they can be used when the acetabular rim is not clearly visible and retroversion is not obvious.

LEVEL OF EVIDENCE

Level III, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Hip capsule dimensions in patients with femoroacetabular impingement: a pilot study

BACKGROUND

Joint-preserving hip surgery, either arthroscopic or open, increasingly is used for the treatment of symptomatic femoroacetabular impingement (FAI). As a consequence of surgery, thickening of the joint capsule and intraarticular adhesions between the labrum and joint capsule and between the femoral neck and the joint capsule have been observed. These alterations are believed to cause persistent pain and reduced range of motion. Because the diagnosis is made with MR arthrography, knowledge of the normal capsular anatomy and thickness on MRI in patients is important. To date there is no such information available.

QUESTIONS/PURPOSES

The purpose of this study was to establish thickness, length of the hip capsule, and the size of the perilabral recess in patients with FAI.

METHODS

We reviewed the preoperative MR arthrography of 30 patients (15 men) with clinical symptoms of FAI. We measured capsular thickness and made observations on the perilabral recess.

RESULTS

The joint capsule was thickest (6 mm) anterosuperiorly between 1 and 2 o'clock. The average length from the femoral head-neck junction to the femoral insertion of the capsule ranged from 19 to 33 mm. A perilabral recess was present circumferentially, even across the acetabular notch, where the labrum is supported by the transverse acetabular ligament. The shortest recess occurred superiorly.

CONCLUSIONS

Knowledge of the capsular anatomy in patients with FAI before surgery is important to judge the postoperative changes and to plan potential further therapy including arthroscopic treatment of intraarticular adhesions.

Does bone wax induce a chronic inflammatory articular reaction?

BACKGROUND

Bone wax is used to control femoral neck bleeding during open femoroacetabular impingement (FAI) surgery. Despite its widespread use, only a few case reports and small case series describe side effects after extraarticular use. It is unclear whether intraarticular use of bone wax leads to such complications. However, during revision FAI surgery, we have observed various degrees of articular inflammatory reactions.

QUESTIONS/PURPOSES

We therefore investigated whether the bone wax used intraarticularly to control femoral neck bleeding during FAI surgery could be associated with the inflammatory reactions observed at revision surgery.

METHODS

We visually inspected the area and analyzed biopsy specimens from all 14 patients undergoing revision surgery from March 2005 to March 2006, 11 of whom had bone wax used at the time of original surgery. The three patients who did not have bone wax were used as controls.

RESULTS

Bone wax was identified macroscopically on the femoral neck at the time of the revision surgery in all 11 patients. In all 11 patients, biopsy results indicated a foreign body-type chronic synovial inflammation. Five patients also had an associated synovial lymphoplasmacytic inflammatory reaction. No inflammatory reaction was observed in the biopsy specimens obtained from the three patients in whom bone wax was not originally used.

CONCLUSIONS

Our findings suggest a synovial foreign body reaction, with or without an associated lymphoplasmacytic chronic inflammatory reaction, may be associated with intraarticular use of bone wax.

The Pararectus approach for anterior intrapelvic management of acetabular fractures

A new anterior intrapelvic approach for the surgical management of displaced acetabular fractures involving predominantly the anterior column and the quadrilateral plate is described. In order to establish five ‘windows’ for instrumentation, the extraperitoneal space is entered along the lateral border of the rectus abdominis muscle. This is the so-called ‘Pararectus’ approach. The feasibility of safe dissection and optimal instrumentation of the pelvis was assessed in five cadavers (ten hemipelves) before implementation in a series of 20 patients with a mean age of 59 years (17 to 90), of whom 17 were male. The clinical evaluation was undertaken between December 2009 and December 2010. The quality of reduction was assessed with post-operative CT scans and the occurrence of intra-operative complications was noted. In cadavers, sufficient extraperitoneal access and safe instrumentation of the pelvis were accomplished. In the patients, there was a statistically significant improvement in the reduction of the fracture (pre- versus post-operative: mean step-off 3.3 mm (sd 2.6) vs 0.1 mm (sd 0.3), p < 0.001; and mean gap 11.5 mm (sd 6.5) vs 0.8 mm (sd 1.3), p < 0.001). Lesions to the peritoneum were noted in two patients and minor vascular damage was noted in a further two patients. Multi-directional screw placement and various plate configurations were feasible in cadavers without significant retraction of soft tissues.

In the treatment of acetabular fractures predominantly involving the anterior column and the quadrilateral plate, the Pararectus approach allowed anatomical restoration with minimal morbidity related to the surgical access.

Prevalence and impact of pain at the greater trochanter after open surgery for the treatment of femoro-acetabular impingement

BACKGROUND

Femoro-acetabular impingement can cause pain and degenerative changes of the hip joint. Traditionally, surgical dislocation of the hip joint has been performed for correction of pathologic abnormalities in the proximal part of the femur and the acetabulum. Failures of surgical treatment are often related to postoperative pain in the groin or in the area of the greater trochanter, associated with this surgical approach. The aim of our study was to determine the prevalence and functional impact of pain at the greater trochanter after surgical dislocation of the hip.

METHODS

Fifty consecutive patients in whom femoro-acetabular impingement had been treated with surgical dislocation of the hip at our institution were seen for clinical and radiographic follow-up at one year. The Merle d'Aubigné score was calculated preoperatively and at the time of follow-up. Pain in the groin or at the greater trochanter during activity and at rest was recorded.

RESULTS

The mean Merle d'Aubigné score significantly improved from 14.4 points preoperatively to 17 points postoperatively. Preoperatively, eight patients (16%) had pain over the greater trochanter. At one year after surgery, twenty-three (46%) had such pain; these patients were primarily female (seventeen of the twenty-three). The mean Merle d'Aubigné score was 17.4 points for the patients without groin pain and 16.1 points for those with groin pain. The presence or absence of pain at the greater trochanter had no significant influence on the outcome, but groin pain was associated with inferior results.

CONCLUSIONS

Tenderness or pain over the greater trochanter is frequent after osteotomy of the greater trochanter and has a distinct female predominance. However, it has no significant negative influence on outcome. This is in contrast to groin pain, which is associated with inferior results.

Surgical dislocation of the hip for a locked traumatic posterior dislocation with associated femoral neck and acetabular fractures

Traumatic posterior dislocation of the hip associated with a fracture of the posterior acetabular wall and of the neck of the femur is a rare injury. A 29-year-old man presented at a level 1 trauma centre with a locked posterior dislocation of the right hip, with fractures of the femoral neck and the posterior wall of the acetabulum after a bicycle accident. An attempted closed reduction had failed. This case report describes in detail the surgical management and the clinical and radiological outcome. Open reduction and fixation with preservation of the intact retinaculum was undertaken within five hours of injury with surgical dislocation of the hip and a trochanteric osteotomy. Two years after operation the function of the injured hip was good. Plain radiographs and MR scans showed early signs of osteoarthritis with some loss of joint space but no evidence of avascular necrosis. The patient had begun skiing and hiking again. The combination of fractures of the neck of the femur and of the posterior wall of the acetabulum hampers closed reduction of a posterior dislocation of the hip. Surgical dislocation of the hip with trochanteric flip osteotomy allows controlled open reduction of the fractures, with inspection of the hip joint and preservation of the vascular supply.

Arthroscopically assisted removal of intraosseous ganglion cysts of the distal tibia

Intraosseous ganglia of the distal tibia are rare. We evaluated the feasibility of surgically treating these lesions with an arthroscopically assisted technique. Five patients with symptomatic distal tibial ganglia underwent surgical curettage and excision with this technique. All patients underwent débridement of the chondral lesion and hypertrophied synovial lining when present, probing of the portal to the ganglion, and subsequently thorough curettage with bone grafting performed through a cortical window made from a separate small incision. Biopsy confirmed the diagnosis in all patients. All patients had eventual relief of symptoms with good integration of bone graft at final followup. There were no recurrences at a minimum followup of 19 months (mean, 38.6 months; range, 19-69 months). Mean time for return to full function was 15.4 weeks (range, 8-17 weeks). There were no intraoperative or postoperative complications. The mean American Orthopaedic Foot and Ankle Society scores increased from 73 points (range, 67-77 points) preoperatively to 94 points (range, 90-100 points) postoperatively. Arthroscopically assisted surgical treatment of ganglia of the distal tibia in the appropriate patient is a reasonably simple technique that relieves symptoms and helps the patient to regain normal gait and full function with no recurrence (in our small series).

LEVEL OF EVIDENCE

Level IV, case series. See Guidelines for Authors for a complete description of levels of evidence.

Real time, confocal imaging of Ca(2+) waves in arterially perfused rat hearts

OBJECTIVE

The aim of this study was to characterize the spatio-temporal dynamics of slow Ca(2+) waves (SCW's) with cellular resolution in the arterially-perfused rat heart.

METHODS

Wister rat hearts were Langendorff-perfused with Tyrode solution containing bovine-albumine and Dextran. The heart was loaded with the Ca(2+) sensitive dye Fluo-3 AM. Intracellular fluorescence changes reflecting changes in [Ca(2+)](i) were recorded from subepicardial tissue layers using a slit hole confocal microscope with an image intensified video camera system at image rates of up to 50/s.

RESULTS

SCW's appeared spontaneously during cardiac rest or after trains of electrical stimuli. They were initiated preferentially in the center third of the cell and propagated to the cell borders, suggesting a relation between the cell nucleus and wave initiation. They were suppressed by Ca(2+) transients and their probability of occurrence increased with the Ca(2+) resting level. Propagation velocity within myocytes (40 to 180 microm/s) decreased with the resting Ca(2+) level. Intercellular propagation was mostly confined to two or three cells and occurred bi-directionally. Intercellular unidirectional conduction block and facilitation of SCW's was occasionally observed. On average 10 to 20% of cells showed non-synchronized simultaneous SCW's within a given area in the myocardium.

CONCLUSIONS

SCW's occurring at increased levels of [Ca(2+)](i) in normoxic or ischemic conditions are mostly confined to two or three cells in the ventricular myocardium. Spatio-temporal summation of changes in membrane potential caused by individual SCW's may underlie the generation of triggered electrical ectopic impulses.