Physiological stretching induces a differential extracellular matrix gene expression response in acetabular labrum cells

The acetabular labrum is a fibrocartilaginous ring surrounding the acetabulum and is important for hip stability and contact pressure dissipation through a sealing function. Injury of the labrum may contribute to hip-joint degeneration and development of secondary osteoarthritis. Understanding how extracellular matrix (ECM) production and remodelling is regulated is of key importance for successful tissue restoration. The present study hypothesised that physiological stretching enhanced the metabolic activity and altered the ECM gene expression in labrum cells. Primary bovine labrum cells were physiologically stretched for up to 5 d. 24 h after the last stretch cycle, changes in metabolic activity were measured using the PrestoBlue™ HS Cell Viability Reagent and ECM gene expression was examined using the quantitative polymerase chain reaction method. Targets of interest were further investigated using immunofluorescence and enzyme-linked immunosorbent assay. Metabolic activity was not affected by the stretching (0.9746 ± 0.0614, p > 0.05). Physiological stretching upregulated decorin (DCN) (1.8548 ± 0.4883, p = 0.002) as well as proteoglycan 4 (PRG4) (1.7714 ± 0.6600, p = 0.029) and downregulated biglycan (BGN) (0.7018 + 0.1567, p = 0.008), cartilage oligomeric matrix protein (COMP) (0.5747 ± 0.2650, p = 0.029), fibronectin (FN1) (0.5832 ± 0.0996, p < 0.001) and spondin 1 (SPON1) (0.6282 ± 0.3624, p = 0.044) gene expression. No difference in PRG4 and DCN abundance or release could be measured. The here identified mechanosensitive targets are known to play relevant roles in tissue organisation. Therefore, physiological stretching might play a role in labrum tissue homeostasis and regeneration.

Is hip morphology a risk factor for developing hip osteoarthritis? A systematic review with meta-analysis

OBJECTIVE

To appraise the highest evidence on hip morphology as a risk factor for developing hip osteoarthritis (OA).

DESIGN

We searched for studies evaluating the association between radiological hip morphology parameters and the prevalence, incidence or progression of hip OA (based on different radiographic and clinical criteria) in the MEDLINE, EMBASE, Web of Science, Scopus, Cochrane Library and PEDro databases from inception until June 2020. Prospective and cross-sectional studies were separately evaluated. Data are presented as odds ratios (OR) with 95% confidence intervals (CI).

RESULTS

We included 9 prospective and 21 cross-sectional studies in the meta-analysis, and evaluated 42,831 hips from 25,898 individuals (mean age: 59 years). Prospective studies showed that, compared with control hips, hips with cam morphology (alpha angle >60°; OR = 2.52, 95% CI: 1.83 to 3.46, P < 0.001) or hip dysplasia (lateral center-edge angle (LCEA) <25°; OR = 2.38, 95% CI: 1.84 to 3.07, P < 0.001), but not hips with pincer morphology (LCEA >39°; OR = 1.08, 95% CI: 0.57 to 2.07, P = 0.810), were more likely to develop hip OA than hips without these morphologies. Cross-sectional studies showed a greater prevalence of pincer morphology (LCEA >39°, OR = 3.71, 95% CI: 2.98 to 4.61, P < 0.001) and acetabular retroversion (crossover sign; OR = 2.65, 95% CI: 1.17 to 6.03, P = 0.020) in hips with OA than in control hips.

CONCLUSION

Cam morphology and hip dysplasia were consistently associated with the development of hip OA. Pincer morphology was associated with hip OA in cross-sectional but not in prospective studies. The heterogeneous quantification of pincer morphology on radiographs limits a clear conclusion on its association with hip OA.

Computer-assisted femoral head reduction osteotomies: an approach for anatomic reconstruction of severely deformed Legg-Calvé-Perthes hips. A pilot study of six patients

BACKGROUND

Legg-Calvé-Perthes (LCP) is a common orthopedic childhood disease that causes a deformity of the femoral head and to an adaptive deformity of the acetabulum. The altered joint biomechanics can result in early joint degeneration that requires total hip arthroplasty. In 2002, Ganz et al. introduced the femoral head reduction osteotomy (FHRO) as a direct joint-preserving treatment. The procedure remains one of the most challenging in hip surgery. Computer-based 3D preoperative planning and patient-specific navigation instruments have been successfully used to reduce technical complexity in other anatomies. The purpose of this study was to report the first results in the treatment of 6 patients to investigate whether our approach is feasible and safe.

METHODS

In this retrospective pilot study, 6 LCP patients were treated with FHRO in multiple centers between May 2017 and June 2019. Based on patient-specific 3D-models of the hips, the surgeries were simulated in a step-wise fashion. Patient-specific instruments tailored for FHRO were designed, 3D-printed and used in the surgeries for navigating the osteotomies. The results were assessed radiographically [diameter index, sphericity index, Stulberg classification, extrusion index, LCE-, Tönnis-, CCD-angle and Shenton line] and the time and costs were recorded. Radiologic values were tested for normal distribution using the Shapiro-Wilk test and for significance using Wilcoxon signed-rank test.

RESULTS

The sphericity index improved postoperatively by 20% (p = 0.028). The postoperative diameter of the femoral head differed by only 1.8% (p = 0.043) from the contralateral side and Stulberg grading improved from poor coxarthrosis outcome to good outcome (p = 0.026). All patients underwent acetabular reorientation by periacetabular osteotomy. The average time (in minutes) for preliminary analysis, computer simulation and patient-specific instrument design was 63 (±48), 156 (±64) and 105 (±68.5), respectively.

CONCLUSION

The clinical feasibility of our approach to FHRO has been demonstrated. The results showed significant improvement compared to the preoperative situation. All operations were performed by experienced surgeons; nevertheless, three complications occurred, showing that FHRO remains one of the most complex hip surgeries even with computer assistance. However, none of the complications were directly related to the simulation or the navigation technique.

Findings and Management of the Rare Caput Flexum Deformity of the Hip: A Case Report

CASE

A 10-year-old girl presented after possible occult hip trauma, with shortening of the leg being the initial clinical symptom, followed by motion-dependent pain. She had limited external rotation in extension with anterior apprehension. Radiographically, the deformity was an anterior tilt of the epiphysis with coxa vara. Surgery included surgical dislocation using a retinacular flap for the anterior open wedge femoral neck osteotomy for extension and posterior translation, with an excellent 4.5-year clinical outcome.

CONCLUSIONS

Caput flexum is a rare deformity with localized premature closure of the anterior growth plate of the hip. To avoid secondary impingement, an osteotomy was successfully placed close to the deformity.

Skin crease ‘bikini’ incision for the direct anterior approach in total hip arthroplasty

Aims

The classical longitudinal incision used for the direct anterior approach (DAA) to the hip does not follow the tension lines of the skin and can lead to impaired wound healing and poor cosmesis. The purpose of this retrospective study was to determine the satisfaction with the scar, and functional and radiographic outcomes comparing the classic longitudinal incision with a modified skin crease ‘bikini’ when the DAA is used for total hip arthroplasty (THA).

Patients and Methods

A total of 964 patients (51% female; 59% longitudinal, 41% ‘bikini’) completed a follow-up questionnaire between two and four years postoperatively, including the Oxford Hip Score (OHS), the University of North Carolina ‘4P’ scar scale (UNC4P) and two items for assessing the aesthetic appearance of the scar and symptoms of numbness. The positioning of the components, rates of heterotopic ossification (HO) and rates of revision were assessed.

Results

The mean OHS was similar in both groups (p = 0.41). The mean UNC4P total score was slightly better (p = 0.01) and the proportion of patients who were very satisfied with the cosmetic aspects of the scar was higher in the ‘bikini’ group (p < 0.001). The proportion of patients reporting numbness in the scar was higher in the longitudinal group (14.5% vs 7.5%, respectively, p < 0.001). The abduction angle of the acetabular component, the position of the stem and rates of HO did not differ between the groups. There were no differences in the revision rates of both groups, being 2.3% in the longitudinal and 1.5% in the ‘bikini’ group (p = 0.911).

Conclusion

We found that a short oblique ‘bikini’ skin crease incision is safe when used for the DAA at THA, without compromising the positioning of the components or increasing the rate of lateral femoral cutaneous nerve dysaesthesia. Although it leads to a superior scar satisfaction, as it is less extensile, it should be used after having gained experience with the classic longitudinal incision. Cite this article: Bone Joint J 2018;100-B:853–61.

Femoral and acetabular re-alignment in slipped capital femoral epiphysis

NEW PATHOPHYSIOLOGICAL INSIGHTS

Based on improved knowledge of the vascular supply of the proximal femur, a safe surgical dislocation of the hip joint was established allowing direct insights to the pathomorphological malfunctioning of the joint. One insight was that slipped capital femoral epiphysis (SCFE) impingement leads to substantial damage of the chondrolabral rim area, even in the presence of minor slips. A further surgical development was the extended retinacular flap allowing for correction of the deformity with calculable risk for iatrogenic necrosis.

CONSECUTIVE SURGICAL CONCEPT

In 20 years of experience, a treatment concept for SCFE could be established which replaces classic pinning in situ and indirect correction of the deformity with subcapital re-alignment when the physis is still open, with true femoral neck osteotomy for hips with closed physis. Pinning in situ still has a place in minor slips but should be combined with open or arthroscopic recreation of an anterior metaphyseal waisting.

UNEXPECTED COMPLICATION

Loss of joint stability is a rare complication of anatomic re-alignment. It can be disease-related when the impingement has induced severe destruction of acetabular cartilage. It can be related to the surgical procedure, especially when the neck was excessively shortened and refixation of the trochanter was not advanced. Finally, in cases with severe and long-lasting deformity, the acetabulum may undergo adaptive flattening, being the cause of joint destabilisation with the correction of the deformity. Advancement of the greater trochanter and/or peri-acetabular osteotomy may be discussed to restabilise the joint.

Instability of the hip after anatomical re-alignment in patients with a slipped capital femoral epiphysis

AIMS

Several studies have reported the safety and efficacy of subcapital re-alignment for patients with slipped capital femoral epiphysis (SCFE) using surgical dislocation of the hip and an extended retinacular flap. Instability of the hip and dislocation as a consequence of this surgery has only recently gained attention. We discuss this problem with some illustrative cases.

MATERIALS AND METHODS

We explored the literature on the possible pathophysiological causes and surgical steps associated with the risk of post-operative instability and articular damage. In addition, we describe supplementary steps that could be used to avoid these problems.

RESULTS

The causes of instability may be divided into three main groups: the first includes causes directly related to SCFE (acetabular labral damage, severe abrasion of the acetabular cartilage, flattening of the acetabular roof and a bell-shaped deformity of the epiphysis); the second, causes not related to the SCFE (acetabular orientation and poor quality of the soft tissues); the third, causes directly related to the surgery (capsulotomy, division of the ligamentum teres, shortening of the femoral neck, pelvi-trochanteric impingement, previous proximal femoral osteotomy and post-operative positioning of the leg).

CONCLUSION

We present examples drawn from our clinical practice, as well as possible ways of reducing the risks of these complications, and of correcting them if they happen. Cite this article: Bone Joint J 2017;99-B:16-21.

Simultaneous versus staged bilateral direct anterior Total Hip Arthroplasty: Are early patient-centered outcomes equivalent?

While accumulating data on the direct anterior approach to total hip arthroplasty (THA) have demonstrated clinical benefit and durable results, there is little data that exists on patient-centered outcomes and satisfaction when comparing simultaneous bilateral procedures with staged arthroplasty. The aim of this study was to determine whether simultaneous bilateral THA and staged arthroplasty result in equivalent early (1) patient-centered outcomes and patient satisfaction; while maintaining acceptable rates of (2) objective clinical outcome scores, (2) complication rates; and (3) radiographic results. In retrospective review, 41 patients who underwent bilateral one-stage THA were compared to 44 patients who underwent staged bilateral THA during the same time period. The minimum clinical follow up was two years. Generic (EQ-VAS and EuroQoL-5D index) and condition-specific (Oxford Hip Score) instruments were used to assess patient-reported outcomes. Other variables included length of hospital stay (LOS), operative and anesthetic times, blood loss, intra- and post-operative (local and systemic) complications, and radiographic analysis. No significant differences between the two groups were found for patient-reported outcomes, complications, or radiographic assessment. The simultaneous THA group had shorter LOS and operative and anesthetic times, as well as less blood loss.

Corrigendum. Intraoperative fluoroscopic imaging to treat cam deformities: correlation with 3-dimensional computed tomography

Ross JR, Bedi A, Stone RM, Sibilsky Enselman E, Leunig M, Kelly BT, Larson CM. Intraoperative fluoroscopic imaging to treat cam deformities: correlation with 3-dimensional computed tomography. Am J Sports Med. 2014;42(6):1370-1376. (Original DOI: 10.1177/0363546514529515 )

The evolution and concepts of joint-preserving surgery of the hip

The use of joint-preserving surgery of the hip has been largely abandoned since the introduction of total hip replacement. However, with the modification of such techniques as pelvic osteotomy, and the introduction of intracapsular procedures such as surgical hip dislocation and arthroscopy, previously unexpected options for the surgical treatment of sequelae of childhood conditions, including developmental dysplasia of the hip, slipped upper femoral epiphysis and Perthes’ disease, have become available. Moreover, femoroacetabular impingement has been identified as a significant aetiological factor in the development of osteoarthritis in many hips previously considered to suffer from primary osteoarthritis.

As mechanical causes of degenerative joint disease are now recognised earlier in the disease process, these techniques may be used to decelerate or even prevent progression to osteoarthritis. We review the recent development of these concepts and the associated surgical techniques.

Cite this article: Bone Joint J 2014;96-B:5–18.

Prevalence of cam and pincer-type deformities on hip MRI in an asymptomatic young Swiss female population: a cross-sectional study

OBJECTIVES

Femoroacetabular impingement is proposed to cause early osteoarthritis (OA) in the non-dysplastic hip. We previously reported on the prevalence of femoral deformities in a young asymptomatic male population. The aim of this study was to determine the prevalence of both femoral and acetabular types of impingement in young females.

METHODS

We conducted a population-based cross-sectional study of asymptomatic young females. All participants completed a set of questionnaires and underwent clinical examination of the hip. A random sample was subsequently invited to obtain magnetic resonance images (MRI) of the hip. All MRIs were read for cam-type deformities, increased acetabular depths, labral lesions, and impingement pits. Prevalence estimates of cam-type deformities and increased acetabular depths were estimated, and relationships between deformities and signs of joint damage were examined using logistic regression models.

RESULTS

The study included 283 subjects, and 80 asymptomatic females with a mean age of 19.3 years attended MRI. Fifteen showed some evidence of cam-type deformities, but none were scored to be definite. The overall prevalence was therefore 0% [95% confidence interval (95% CI) 0-5%]. The prevalence of increased acetabular depth was 10% (95% CI 5-19). No association was found between increased acetabular depth and decreased internal rotation of the hip. Increased acetabular depth was not associated with signs of labral damage.

CONCLUSIONS

Definite cam-type deformities in women are rare compared to men, whereas the prevalence of increased acetabular depth is higher, suggesting that femoroacetabular impingement has different gender-related biomechanical mechanisms.

Fulfilment of patient-rated expectations predicts the outcome of surgery for femoroacetabular impingement

OBJECTIVE

The aim of this study was to explore the role of expectations in relation to patient-rated global treatment outcome in patients undergoing hip preservation surgery for femoroacetabular impingement (FAI).

METHOD

Pre-operatively, 86 patients completed the Oxford Hip Score (OHS), a question about the motivation for undergoing surgery, and Likert-scales rating the improvement expected in various domains (pain, general function, sport, walking capacity, independence, social function, mental well-being). 12-months post-operatively, they rated the actual perceived improvement in each domain and the global outcome of surgery (GTO, 5-point Likert-scale: operation "helped a lot" through to "made things worse"), and completed the OHS again.

RESULTS

The most frequent "top reason" for surgery was "alleviation of pain", being indicated by 33% patients; 20% patients chose "fear of worsening", 16% "improvement in everyday activities", 11% "other therapies failed", 10% "improvement in sporting activities" and 10% other. The 12-month data revealed prior expectations had been overly optimistic in more than 50% patients for hip pain, sport, and general physical capacity, and in 33-45% patients for independence, mental well-being, and walking capacity. Multiple regression revealed significant (P<0.05) unique associations between GTO and "fulfilled expectations" for pain and sport (explaining 47% and 12% variance, respectively).

CONCLUSION

Expectations of surgery were overly optimistic. Having one's expectations fulfilled, especially in relation to pain, was important for a good outcome. The results emphasise the benefit of assessing patient-orientated outcome in routine practice and the factors that might influence it, such that realistic expectations can be established for patients prior to surgery.

The pathoanatomy and arthroscopic management of femoroacetabular impingement

Femoroacetabular impingement (FAI) causes pain and chondrolabral damage via mechanical overload during movement of the hip. It is caused by many different types of pathoanatomy, including the cam 'bump', decreased head-neck offset, acetabular retroversion, global acetabular overcoverage, prominent anterior-inferior iliac spine, slipped capital femoral epiphysis, and the sequelae of childhood Perthes' disease. Both evolutionary and developmental factors may cause FAI. Prevalence studies show that anatomic variations that cause FAI are common in the asymptomatic population. Young athletes may be predisposed to FAI because of the stress on the physis during development. Other factors, including the soft tissues, may also influence symptoms and chondrolabral damage. FAI and the resultant chondrolabral pathology are often treated arthroscopically. Although the results are favourable, morphologies can be complex, patient expectations are high and the surgery is challenging. The long-term outcomes of hip arthroscopy are still forthcoming and it is unknown if treatment of FAI will prevent arthrosis.

The early outcome of surgical treatment for femoroacetabular impingement: success depends on how you measure it

OBJECTIVE

To evaluate the proportion of "successes" after surgery for femoroacetabular impingement (FAI) using different external criteria, "feeling better" and "feeling good", and to determine the corresponding cut-off scores indicating "success" for the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) (0-10-point response scale), Oxford Hip Score (OHS) and EuroQoL-5D (EQ-5D and EQ-VAS).

DESIGN

Prospective, observational study based in an orthopaedic hospital. Ninety-nine consecutive patients with FAI completed the questionnaires before and 6 months after surgery (arthroscopy or mini-open surgical dislocation). Patient-ratings of change in state ("feeling better") were assessed using a global treatment outcome (GTO) item. Acceptability of the current health state was assessed using the symptom-specific well-being (SSWB) item. Cut-off (threshold) scores for the different instruments indicating the minimal clinically important change (MCIC) and acceptable symptom state were calculated using Receiver Operating Characteristics (ROC) analyses.

RESULTS

Significant improvements in all scores (P < 0.001) were recorded 6 months after surgery. The proportion of good outcomes measured with GTO was 60%; 55% of patients reported having achieved an acceptable symptom state. The MCIC scores for improvement were ≥6 for the OHS (0-48 total score range), ≥15 for EQ-VAS, ≥0.16 for EQ-5D index, and ≥22 for the WOMAC-total score (0-100 total score range); absolute scores of ≥40, ≥80, ≥0.682 and ≤8, respectively, were associated with an acceptable symptom state.

CONCLUSIONS

The results show that feeling better does not always equate to feeling good, and that improvements in outcome scores, even large, do not necessarily indicate acceptability of the current state. The cut-off values may help in the interpretation of trial results and individual change-scores recorded in clinical practice.

Use of multimodal intra-operative monitoring in averting nerve injury during complex hip surgery

Peripheral nerve injury is an uncommon but serious complication of hip surgery that can adversely affect the outcome. Several studies have described the use of electromyography and intra-operative sensory evoked potentials for early warning of nerve injury. We assessed the results of multimodal intra-operative monitoring during complex hip surgery. We retrospectively analysed data collected between 2001 and 2010 from 69 patients who underwent complex hip surgery by a single surgeon using multimodal intra-operative monitoring from a total pool of 7894 patients who underwent hip surgery during this period. In 24 (35%) procedures the surgeon was alerted to a possible lesion to the sciatic and/or femoral nerve. Alerts were observed most frequently during peri-acetabular osteotomy. The surgeon adapted his approach based on interpretation of the neurophysiological changes. From 69 monitored surgical procedures, there was only one true positive case of post-operative nerve injury. There were no false positives or false negatives, and the remaining 68 cases were all true negative. The sensitivity for predicting post-operative nerve injury was 100% and the specificity 100%. We conclude that it is possible and appropriate to use this method during complex hip surgery and it is effective for alerting the surgeon to the possibility of nerve injury.

Survivorship of second-generation metal-on-metal primary total hip replacement

BACKGROUND

Second generation metal-on-metal total hip replacements (THR) were introduced in the late 1980s and various studies reported conflicting data on their outcome.

METHODS

Implant survival of 1,270 second-generation 28 mm metal-on-metal primary THR in 1,121 patients followed prospectively at a mean of 6.8 years postoperatively was evaluated retrospectively. The probability of survival at 10 years was estimated using the method of Kaplan and Meier, and relative risk factors including age, gender, BMI, type of implant fixation and component size were calculated using the Cox proportional-hazards model.

RESULTS

Sixty-three (5%) THRs were revised, these being 28 hips for aseptic loosening and 35 for reasons other than aseptic loosening. The probability of survival at 10 years, with revision for any reason as the endpoint, was 0.90 (95% confidence interval (CI) 0.86-0.94) for the THR as a whole, 0.91 (95% CI 0.87-0.95) for the cup, and 0.96 (95% CI 0.94-0.98) for the stem. No demographic factors or covariates were found to significantly affect the implant survivorship.

DISCUSSION

As there was no superior probability of survival, and there have been concerns on putative local and systemic toxicity of metal debris, the use of second-generation metal-on-metal articulations for primary THR remains moot.

Hip resurfacing arthroplasty: current status and future perspectives

Hip resurfacing arthroplasty (HRA) is a concept of hip replacement that allows treating young active patients with a femoral bone preserving procedure. The proposed advantages of resuming an active lifestyle with increased frequency and duration of sports activities have been shown to be realistic. The 30-year cost-effectiveness in young male patients has been shown to be higher in resurfacing compared to conventional total hip replacement (THA). However, prognosticators of an inferior outcome have also been identified. The most important patient related factors are secondary osteoarthritis as the indication for surgery such as post-childhood hip disorders or AVN, female gender, smaller component sizes and older age (>65 years for males and >55 years for females). In addition, surgical technique (approach and cementing technique) and component design are also important determinant factors for the risk of failure. Moreover, concerns have surfaced with respect to high metal ion concentrations and metal ion hypersensitivities. In addition, the presumed ease of revising HRA has not reflected in improved or equal survivorship in comparison to a primary THA. This highlights the importance of identifying patient-, surgery-, and implant-related prognosticators for success or failure of HRA. Rather than vilifying the concept of hip resurfacing, detailed in depth analysis should be used to specify indications and improve implant design and surgical techniques.

Histopathology of Cryopreserved Bone Allo- and Isografts: Pretreatment with Dimethyl Sulfoxide

Partial graft cell survival and enhanced graft revascularization have suggested fast freezing using the cryoprotective substance dimethyl sulfoxide (DMSO) as a promising means to improve the biologic function and immune tolerance of allograft bone. This study determines the presence of osteoblasts (cola(1)(I) mRNA), osteoclasts (TRAP), and cytotoxic T cells (CTLs; GrA mRNA) within pretreated bone grafts 12 days after transplantation. The grafts were transplanted either as isografts, allografts, or allografts in presensitized recipients. In fresh isografts, serving as control, well-formed blood vessels and the highest numbers of viable osteoblasts and osteoclasts were found. In fresh allografts, blood vessels were observed within the marrow cavity and the bone was partially covered by osteoblasts and osteoclasts accompanied by CTLs. In DMSO-pretreated frozen allografts, blood vessels together with osteoblasts were observed in three of five, but in none of five grafts frozen without DMSO. However, infiltration with CTLs was higher in DMSO-pretreated frozen allografts when compared to grafts frozen without DMSO. In presensitized allograft recipients, independent of the pretreatment, in none of the grafts were either blood vessels or osteoblasts found. Thus, fast cryopreservation of bone using DMSO improves vascularization and expression of cola(1)(I) mRNA (osteoblasts) after allografting when compared to cryopreservation alone, potentially improving graft incorporation. As these grafts were still invaded by CTLs, the long-term effect of DMSO pretreatment needs to be defined.

Differential response of porcine osteoblasts and chondrocytes in cell or tissue culture after 5-aminolevulinic acid-based photodynamic therapy

OBJECTIVE

Outcome in osteochondral allografting is limited by the immunological incompatibility of the grafted tissue. Based on a resistance of chondrocytes to photodynamic therapy in cell culture it is proposed that 5-aminolevulinic acid-based photodynamic therapy (5-ALA-PDT) might be used to inactivate bone while maintaining viability of chondrocytes and thus immunomodulate bone selectively.

METHODS

Chondrocytes and osteoblasts from porcine humeral heads were either isolated (cell culture) or treated in situ (tissue culture). To quantify cytotoxic effects of 5-ALA-PDT (0-20 J/cm(2), 100 mW/cm(2)) an (3-(4,5-dimethylthiazol-2-yl)-2,5-di-phenyltetrazolium bromide) (MTT)-assay was used in cell culture and in situ hybridization in tissue culture to assess metabolic active cells (functional osteoblasts: col alpha(1)(I) mRNA, functional chondrocytes: col alpha(1)(II) mRNA).

RESULTS

In cell culture, survival after 5-ALA-PDT was significantly higher for chondrocytes (5 J/cm(2): 87+/-12% compared to untreated cells) than for osteoblasts (5J/cm(2): 12+/-11%). In tissue culture, the percentage of functional chondrocytes in cartilage showed a decrease after 5-ALA-PDT (direct fixation: 92+/-2%, 20 J/cm(2): 35+/-15%; P<0.0001). A significant decrease in the percentage of bone surfaces covered by functional osteoblasts was observed in freshly harvested (31+/-3%) compared to untreated tissues maintained in culture (11+/-4%, P<0.0001), with no further decrease after 5-ALA-PDT.

CONCLUSION

Chondrocytes were more resistant to 5-ALA-PDT than osteoblasts in cell culture, while in tissue culture a loss of functional chondrocytes was observed after 5-ALA-PDT. Since osteoblasts - but not chondrocytes - were sensitive to the tissue culture conditions, devitalized bone with functional cartilage might already be achieved by applying specific tissue culture conditions even without 5-ALA-PDT.

The 12-item Oxford Knee Score: cross-cultural adaptation into German and assessment of its psychometric properties in patients with osteoarthritis of the knee

OBJECTIVE

To cross-culturally adapt and validate the Oxford Knee Score (OKS) for use in German-speaking patients with osteoarthritis of the knee.

METHODS

After the cross-cultural adaptation (OKS-D), the following metric properties of the questionnaire were assessed in 100 consecutive patients (mean age 66.5 years, 61 women) undergoing total knee replacement: feasibility (percentage of fully completed questionnaires), reliability (Intraclass Correlation Coefficients [ICC] and Bland and Altman's limits of agreement), and construct validity (correlation with the Western Ontario and McMaster Universities Index [WOMAC], Knee Society Score [KSS], Activities of Daily Living Scale [ADLS], and Short Form 12 [SF-12]), floor and ceiling effects, and internal consistency (Cronbach's Alpha, CA).

RESULTS

We received 91.9% fully completed questionnaires. Reliability of the OKS-D was excellent (ICC 0.91). Bland and Altman's limits of agreement revealed no significant bias (-0.2) and a random error of 6.2. Correlation coefficients with the other questionnaires ranged from -0.22 (SF-12 Mental Component Scale [MCS]) to -0.77 (ADLS). We observed no floor or ceiling effects. The CA was 0.83.

CONCLUSIONS

The German version of the OKS is a reliable and valid measure for the self-assessment of pain and function in German-speaking patients with osteoarthritis of the knee.

Construct validity of a 12-item WOMAC for assessment of femoro-acetabular impingement and osteoarthritis of the hip

OBJECTIVE

Evaluation of the internal construct validity of the Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index adapted for use in patients with femoro-acetabular impingement (FAI) and osteoarthritis (OA) of the hip.

METHODS

Distribution of a German version of WOMAC to patients upon first consultation. Patients with FAI [n=100, mean age 31.7 years, standard deviation (SD) 9.7] and OA (n=57, mean age 60.3 years, SD 11.7) and without comorbidities or prior hip surgery were included and compared to age- and gender-matched control population to FAI (n=200, mean age 32.6 years, SD 5.6). WOMAC data of 157 questionnaires were evaluated by Rasch analysis using RUMM2020 software.

RESULTS

Summation of total WOMAC shows misfit to the Rasch model as well as multidimensionality. While the pain subset shows adequate fit and is unidimensional, item reduction is required to fit a unidimensional subset of functional items to the Rasch model. Summating the two fitting subsets yields again slight model misfit and multidimensionality requiring further item reduction. Finally, a 12-item version of the total WOMAC shows good model fit and unidimensionality, i.e., internal construct validity, for assessment of patients with FAI and OA without differential item functioning (DIF). A person separation index (PSI)=0.93 indicates a high internal consistency reliability for the 12-item subscale. Scores for FAI are significantly higher than control (P<0.001, effect size 0.71) and lower than OA group (P<0.001, effect size 0.45). Adequate statistical power is shown discriminating the three groups, therefore indicating some evidence also for external construct validity.

CONCLUSIONS

The WOMAC as a total construct is multidimensional and summating the subsets into a total score is not valid. The reduced 12-item WOMAC is demonstrated to have internal construct validity for assessing patients with FAI and OA on the same scale and high internal consistency reliability. Discrimination of the groups with adequate statistical power also indicates external construct validity.

Evaluation and treatment of young adults with femoro-acetabular impingement secondary to Perthes' disease

Hip pain and loss of motion in young adults with previous Legg-Calve-Perthes-Disease may be caused by anterior femoro-acetabular impingement. Eleven patients (12 hips) with the chief complaint of groin pain and significant proximal femoral deformity were treated. Gadolinium-enhanced magnetic resonance arthrography in ten patients indicated labral injury and adjacent acetabular cartilage lesions in nine hips. A surgical dislocation of each hip confirmed that there was impingement induced intra-articular injury consistent with the pathology indicated on the MRI. Reshaping of the femoral head, with correction of the femoral head/neck offset, and treatment of the acetabular rim pathology was performed for each hip in conjunction with other procedures for the proximal femur. Correction of the impingement and increased range of motion could be visualized intra-operatively. At a mean follow-up of 33 months, half of all patients were pain-free and all had improvement in pain compared with preoperatively. Ten patients had an improved range of motion and two a slight decrease. No additional necrosis following the dislocation of the femoral head was seen.;

Acetabular dome retroversion: radiological appearance, incidence and relevance

Interest in acetabular version arose from the study of unstable developmental dysplastic hips (DDH). Initial studies and clinical observations described the dysplastic hip as being excessively anteverted. Doubts on this view arose from analysis of complications such as persistent posterior subluxation after acetabular reorienting procedures. Computed tomography fails to determine conclusively whether or not the dysplastic acetabulum is abnormally anteverted. Controversy evolves from different methods of measuring and from the fact that the acetabular opening gradually spirals from mild anteversion proximally to increasing anteversion distally. This renders the measurement of version dependent on pelvic inclination and the level of the transverse CT scan slice. On an orthograde pelvic radiograph, both pelvic inclination and rotation can be controlled. Therefore, acetabular version is best estimated based on the relationship of the anterior and posterior acetabular rims to each other on an orthograde pelvic radiograph. Acetabular retroversion has been found to be a characteristic feature of specific hip disorders such as post-traumatic dysplasia, proximal femoral focal deficiency and bladder exstrophy. In addition, acetabular retroversion has been described in DDH as well as in dysplastic hips in the context of neuromuscular and genetic disorders. Iatrogenic acetabular retroversion can also result from corrective pelvic osteotomies in childhood. Finally, retroverted acetabula may be found in otherwise nondysplastic hips. The relevance of acetabular retroversion is twofold: First, it demands a more individualized approach to acetabular dysplasia because the presence of retroversion will affect the manner in which the corrective osteotomy should be done. Second, the long-term effect of acetabular retroversion is harmful.

[Femoroacetabular impingement: trigger for the development of coxarthrosis]

Femoroacetabular impingement (FAI) is frequent; the estimated prevalence ranges between 10 and 15%. Our 10-years experience strongly suggests that FAI leads to osteoarthritis. Isolated acetabular or femoral abnormalities are rare, even though in women acetabular and in men femoral abnormalities predominate. Normal radiographs do not exclude the presence of FAI. Symptoms are related to the degree of deformity and occur earlier in the presence of activities requiring high levels of motion. The majority of patients with FAI are under the age of 40 years. In contrast to impingement in total hip replacement, the natural hip is under much higher constraint, not allowing to escape from impingement-induced shear forces by subluxation or complete dislocation. FAI-induced shear forces due to an aspherical femoral head/neck (cam type) are therefore high, causing outside-in damage with cleavage lesions of the acetabular cartilage by forced flexion and internal rotation. The cartilage of the femoral head remains initially intact, which cannot be explained by the classic concept of osteoarthritis. After the femoral head has migrated into the acetabular cartilage defect, vertical forces contribute to the further course of osteoarthritis. Tears between the labrum and cartilage, as seen by MRI, are not avulsions of the labrum from the cartilage but rather outside-in avulsions of the cartilage from the labrum. In acetabular overcoverage (pincer type) the labrum is the first structure to fail and acetabular cartilage damage develops thereafter. The treatment of FAI in patients under the age of 40 years is aimed at joint preservation. The clinical result is worse in the presence of significant cartilage damage. Therefore, early appreciation of FAI and timely therapeutic intervention as well as professional and athletic adjustment are important if osteoarthritis is to be prevented.

Acetabular centre-edge angles revisited: applications and limitations in patients with acetabular dysplasia undergoing periacetabular osteotomy

This study evaluates the application and limitations of the acetabular centre-edge angles as described by Wiberg (LCE) and Lequesne (VCA) in a group of adult patients with acetabular dysplasia that were treated with periacetabular osteotomy. Fifty hips in patients with a mean age of 30 years (range, 17-45) were identified and a number of radiographic indices were compared pre and post osteotomy. The potential for measurement variation in both the LCE and VCA angle was evaluated and relationships between the centre-edge angles and other radiographic indices were determined. While all hips displayed some degree of lateral deficiency only 19 (40%) of these cases displayed a ''classic'' lateral and anterior deficiency while 12 (20%) were in fact retroverted. The mean VCA in hips with primarily anterior and lateral deficiency (-6.712.5) was significantly lower (p<0.01) than those with uniform deficiency (5.18.3) or those with retroverted acetabuli (8.913.3). Overall the mean VCA angle of 2.3 (SD12.7) and LCE angle of 3.4 (SD9.3) was corrected to 25.8 (SD11.6) and 28.6 (SD8.7) following osteotomy. The VCA and LCE angles were not correlated (r=0.35) and the LCE angle showed no significant correlation to other lateral coverage indices (Tnnis, Sharp). No correlation was seen either in the post osteotomy values, or in the absolute degree of correction. An alternate VCA (aVCA), identifying the most anterior aspect of the acetabular margin as the reference point, was significantly larger (p<0.001) but did correlate (r=0.77) with the traditional VCA. Potential sources of error in measurement were identified and are reviewed.

Hip morphology influences the pattern of damage to the acetabular cartilage: femoroacetabular impingement as a cause of early osteoarthritis of the hip

Recently, femoroacetabular impingement has been recognised as a cause of early osteoarthritis. There are two mechanisms of impingement: 1) cam impingement caused by a non-spherical head and 2) pincer impingement caused by excessive acetabular cover. We hypothesised that both mechanisms result in different patterns of articular damage. Of 302 analysed hips only 26 had an isolated cam and 16 an isolated pincer impingement. Cam impingement caused damage to the anterosuperior acetabular cartilage with separation between the labrum and cartilage. During flexion, the cartilage was sheared off the bone by the non-spherical femoral head while the labrum remained untouched. In pincer impingement, the cartilage damage was located circumferentially and included only a narrow strip. During movement the labrum is crushed between the acetabular rim and the femoral neck causing degeneration and ossification. Both cam and pincer impingement lead to osteoarthritis of the hip. Labral damage indicates ongoing impingement and rarely occurs alone.

Femoroacetabul�res Impingement

The exact cause of the idiopathic osteoarthritis of the hip has not been identified, although the cause of hip degeneration in developmental dysplasia can clearly be attributed to an excessive axial loading. Based on the development of a surgical technique for the safe surgical dislocation of the hip and the associated possibility of intraoperative joint evaluation, we have found motion-induced joint damage in many of these hips. This begins peripherally at the acetabular rim, progressing centrally. This so-called "femoroacetabular impingement" (FAI), leads, by an increased acetabular coverage and/or a missing sphericity of the femoral head, to an abutment of the femoral head/neck junction against the acetabular rim, or even entering of the non-spherical femoral head into the hip. It initiates damage to the labrum and/or acetabular cartilage. Frequently, this becomes symptomatic in the second or third decade of life in patients with increased sport activity. Based on the predominance of the acetabular or femoral pathology, two different types of FAI, the pincer and the cam can be differentiated. Apart from these morphological alterations, supraphysiological mobility and overuse can contribute to FAI. The impingement concept has led to a new type of mainly intracapsular hip surgery.

Predictors of humeral head ischemia after intracapsular fracture of the proximal humerus

The purpose of this study was to evaluate predictors of fracture-induced humeral head ischemia. Between February 1998 and December 2001, 100 intracapsular fractures of the proximal humerus, treated by open surgery, were included in a prospective surgical evaluation protocol (mean age, 60 years; minimum, 21 years; maximum, 88 years; 45 men; 57 right shoulders). Fracture morphology was assessed following a structured questionnaire and based on radiographic and intraoperative findings. Perfusion was assessed intraoperatively by observation of backflow after a borehole was drilled into the central part of the head in all shoulders and by intraosseous laser Doppler flowmetry in 46. Good predictors of ischemia were the length of the metaphyseal head extension (accuracy, 0.84 for calcar segments <8 mm), the integrity of the medial hinge (accuracy, 0.79 for disrupted hinge), and the basic fracture pattern (accuracy, 0.7 for combined types 2, 9, 10, 11, and 12). Moderate and poor predictors of ischemia were fractures consisting of four fragments (accuracy, 0.67), angular displacement of the head (accuracy, 0.62 for angulations over 45 degrees ), the amount of displacement of the tuberosities (accuracy, 0.61 for displacement over 10 mm), glenohumeral dislocation (accuracy, 0.49), head-split components (accuracy, 0.49), and fractures consisting of three fragments (accuracy, 0.38). When the above criteria (anatomic neck, short calcar, disrupted hinge) were combined, positive predictive values of up to 97% could be obtained. The most relevant predictors of ischemia were the length of the dorsomedial metaphyseal extension, the integrity of the medial hinge, and the basic fracture type determined with the binary description system.

Abnormal extension of the femoral head epiphysis as a cause of cam impingement

The etiology of an insufficient femoral head-neck offset has not been identified yet. It was investigated whether a decreased head-neck offset might be correlated with an unusual orientation of the physeal capital scar. Therefore, the femoral head-neck offset and the extension of the physeal scar onto the femoral neck were measured with specific magnetic resonance imaging arthrography. The measurements were done in 15 patients with anterior femoroacetabular impingement attributable to a nonspherical head and were compared with 15 age- and gender-matched control subjects. Eight serial magnetic resonance imaging sections perpendicular to the femoral neck axis were used in each hip to measure the head-neck offset and the epiphyseal extension toward the femoral neck at 16 measurement points. In both groups there was an inverse correlation between the amount of head-neck offset and the relative extension of the capital physeal scar in the cranial hemisphere of the head. Within the anterosuperior head quadrant, there was statistically significant different decrease of the head-neck offset and increase of the lateral epiphyseal extension in the patients compared with the control subjects. These findings suggest a growth abnormality of the capital physis as one probable underlying cause for a nonspherical head.

The acetabular blood supply: implications for periacetabular osteotomies

As the popularity of juxta-acetabular osteotomies in adults increases, concern arises that such a procedure will potentially cause avascular necrosis of the acetabular fragment. In order to verify the remaining vascularization after a Bernese periacetabular osteotomy, an injection study with colored latex was performed. The vascularity of the outside of the periacetabular bone was studied in 16 hips after injection of colored latex into the abdominal aorta and the inside in four hips. To confirm the conclusions drawn from the anatomic study, a Bernese periacetabular osteotomy was performed in two additional hips after latex injection. This study demonstrated that through a modified Smith-Peterson approach and with execution of the osteotomies from the inside of the pelvis the acetabular fragment remains vascularized by the supra-acetabular and acetabular branches of the superior gluteal artery, the obturator artery and the inferior gluteal artery. Some uncertainty remains about how much correction is tolerated by the smaller blood vessels.

Cryopreservation with dimethyl sulfoxide sustains partially the biological function of osteochondral tissue

The clinical routine use of bone allograft transplants dates back to the discovery that grafts devitalized by freezing bear a reduced antigenicity. Graft failures, caused by a host versus graft reaction, however, remain a clinical problem. Previous investigations on pancreatic islet allografts revealed improved survival and biological function when fast cryopreservation (-70 degrees C/min) was performed in the presence of dimethyl sulfoxide (DMSO). The aim of this study was to determine the effect of fast freezing using DMSO on the biological function of osteochondral tissues. Organ culture was performed with neonatal femora of mice, untreated, rapidly frozen (-70 degrees C/min) with DMSO, or frozen without DMSO. After the culture, tissue morphology, cellular proliferation, osteoblast function, osteoclasts, and the presence of antigen-presenting cells were investigated. In untreated control femora histology appeared normal and proliferating and collagen-synthesizing osteoblasts, osteoclasts, and B-cells and macrophages were present. In frozen femora (with and without DMSO) a disintegration of the periosteum and the epiphyseal growth plate were observed and no active osteoblasts could be detected. Osteoclasts were partially detached from the bone surface. Cell proliferation was fully blocked in femora frozen in the absence of DMSO, while freezing in the presence of DMSO preserved cell proliferation in the medullary canal. The proliferating cells do not express epitopes present on the cells of the B-cell or macrophage lineages. Although the biological function of osteoblasts and osteoclasts was lost upon freezing of osteochondral tissue, DMSO included in freezing protocols preserves some residual cell viability which may be of importance for early graft revascularization as has been previously demonstrated by our group.

[Early damage to the acetabular cartilage in slipped capital femoral epiphysis. Therapeutic consequences]

Epiphyseolysis capitis femoris represents the most common disorder of the adolescent hip, which is followed by a significant rate of early osteoarthrosis. Based on intraoperative findings during the surgical management of 23 hips with epiphyseolysis, early acetabular cartilage abrasion by a cam effect and acetabular rim impingement elicited by the prominent femoral metaphysis have been identified. Both phenomena cause direct damage to the hip joint, especially during flexion and flexion/internal rotation of the hip. As evidenced during surgery, the prominent and sometimes sharp-edged anterior neck metaphysis leveling or exceeding the femoral head showed marks of contusion and the labrum revealed erosions, scars, or tears. Moreover, adjacent acetabular cartilage damage was present ranging from superficial abrasions to a full thickness cartilage loss propagating into the weight-bearing area. In all patients the femoral head cartilage was intact; no avascular necrosis was present. These findings suggest that osteoarthrosis is triggered by direct mechanical damage in the epiphysiolysis hip already during the process of slipping and that chondrolysis appears to represent just the most severe form of this cartilage damage. Consequently, we propose that treatment should not only address the avoidance of a further slippage but also the prevention of impingement and cam leading to early acetabular cartilage damage.

Early lesions of the labrum and acetabular cartilage in osteonecrosis of the femoral head

Osteonecrosis of the femoral head can be caused by a variety of disorders and affects the relatively young patient. Most studies have concentrated on the femoral changes; the sites of early lesions of the labrum and acetabular cartilage have not been recorded. We studied 17 hips with osteonecrosis and a wide congruent joint space on radiographs and by direct inspection of the femoral head, labrum and acetabular cartilage during surgery. All of the femoral heads had some anterosuperior flattening which reduced the head-neck ratio in this area. A consistent pattern of damage to the labrum and the acetabular cartilage was seen in all hips. Intraoperatively, impingement and the cam-effect with its spatial correlation with lesions of the labrum and acetabular cartilage were observed. These findings could be helpful when undertaking conservative surgery for osteonecrosis, since the recognition of early radiologically undetectable acetabular lesions may require modification of the surgical technique.

Early lesions of the labrum and acetabular cartilage in osteonecrosis of the femoral head

Osteonecrosis of the femoral head can be caused by a variety of disorders and affects the relatively young patient. Most studies have concentrated on the femoral changes; the sites of early lesions of the labrum and acetabular cartilage have not been recorded. We studied 17 hips with osteonecrosis and a wide congruent joint space on radiographs and by direct inspection of the femoral head, labrum and acetabular cartilage during surgery. All of the femoral heads had some anterosuperior flattening which reduced the head-neck ratio in this area. A consistent pattern of damage to the labrum and the acetabular cartilage was seen in all hips. Intraoperatively, impingement and the cam-effect with its spatial correlation with lesions of the labrum and acetabular cartilage were observed. These findings could be helpful when undertaking conservative surgery for osteonecrosis, since the recognition of early radiologically undetectable acetabular lesions may require modification of the surgical technique.

[MR-Arthrography with radial sequences for visualization of early hip pathology not visible on plain radiographs]

AIM

We wanted to improve MRI visualization of early hip pathology invisible on plain radiographs.

METHOD

An MR arthrography of the hip with radial sequences is described. The standard MR technique is improved by 1) using a small flexible surface coil to show selectively the hip joint to be examined, 2) application of gadolinium intra-articularly and 3) by radial imaging sequences perpendicular to the true plane of the acetabulum.

CONCLUSION

By this technique it is possible to achieve an undistorted image of each aspect of the acetabular rim. Regions of special interest can be defined and their pathologies possibly related to morphologies of the proximal end of the femur.

Surgical landmarks to determine humeral head retrotorsion for hemiarthroplasty in fractures

Malrotation has been suggested as a cause of failure of hemiarthroplasty of the proximal humerus. Placing a shoulder prosthesis in relationship to the bicipital groove might reproduce individual anatomy more reliably than using a standardized retrotorsion. The purpose of this study was to determine criteria for accurate adjustment of retrotorsion even when the proximal bicipital groove is destroyed, as is the case in fractures. The distance of the humeral head equatorial plane to the center of the bicipital groove was measured by high-resolution computed tomography at 4 levels (proximal and distal with 2 intermediate levels). The distal distance was considered to correspond to available references in fracture cases. The mean proximal distance was 8.0 mm (10th percentile, 6.2 mm; 90th percentile, 9.8 mm), and the mean distal distance was 8.5 mm (10th percentile, 7.1 mm; 90th percentile, 9.9 mm). As to the clinical relevance, there was no statistically significant difference between distances. For practical purposes in fracture indications, it is adequate to adjust the retrotorsion of the prosthetic component to the distal bicipital groove.

Entry point soft tissue damage in antegrade femoral nailing: a cadaver study

INTRODUCTION

Little attention is paid to insertion site morbidity associated with antegrade femoral nailing. However, residual peritrochanteric pain after nailing is not uncommon. Additionally, the end branches of the medial femoral circumflex artery (m.f.c.a.) supplying the femoral head are in close proximity to the insertion site of the nail, and the occurrence of avascular necrosis of the femoral epiphysis after nailing in adolescents is rather frequent.

OBJECTIVE

The aim of this study was to assess iatrogenic soft tissue injuries at the site of nail insertion.

MATERIALS AND METHODS

Nailing with a reamed AO universal femoral nail was performed on sixteen adult cadavers followed by dissection of the proximal part of the femur to assess possible damage to the soft tissues. Three entry portals were defined. (A) entry portal lateral to the junction of the neck and the greater trochanter; (B) entry portal at the base of the greater trochanter anterior to a line along the longitudinal axis of the femoral neck; and (C) entry portal at the base of the greater trochanter posterior to a line along the axis of the femoral neck (at the piriformis fossa).

RESULTS

In Group A, partial avulsion of the piriformis and the obturator internus tendon were present in four and in one of five specimens, respectively. Group B showed injuries to the piriformis tendon in two and to the gluteus minimus tendon in one of four cases. In Group C, partial avulsion of the piriformis, obturator internus, and obturator externus tendon were encountered in five, six, and two of seven specimens, respectively. Anterior branches of the ramus profundus of the m.f.c.a. within the synovial fold were damaged in all of these cases.

CONCLUSION

To select the best nail entry portal, the ease of nail insertion must be weighed against the resulting soft tissue damage at the site of insertion. The nail entry portal at the piriformis fossa, although geometrically ideal and most recommended, causes the most significant damage to muscle and tendons as well as to the blood supply to the femoral head. Therefore, even if reported only once, the occurrence of avascular necrosis of the femoral head after nailing in adults is a possible complication of this nail entry portal. The authors therefore prefer to avoid this entry portal in every case. The nail entry portal anterior to the longitudinal axis of the femoral neck, as in group B, although better with respect to the soft tissue damage, has the worst geometric and biomechanical disadvantages. The results of the current study favor the nail entry portal lateral at the greater trochanter as in Group A, which is equal to the entry portal B with respect to the soft tissue damage but allows introduction of the nail into the medullar cavity without difficulties.

Femoroacetabular impingement and the cam-effect. A MRI-based quantitative anatomical study of the femoral head-neck offset

We have observed damage to the labrum as a result of repetitive acetabular impingement in non-dysplastic hips, in which the femoral neck appears to abut against the acetabular labrum and a non-spherical femoral head to press against the labrum and adjacent cartilage. In both mechanisms anatomical variations of the proximal femur may be a factor. We have measured the orientation of the femoral neck and the offset of the head at various circumferential positions, using MRI data from volunteers with no osteoarthritic changes on standard radiographs. Compared with the control subjects, paired for gender and age, patients showed a significant reduction in mean femoral anteversion and mean head-neck offset on the anterior aspect of the neck. This was consistent with the site of symptomatic impingement in flexion and internal rotation, and with lesions of the adjacent rim. Furthermore, when stratified for gender and age, and compared with the control group, the mean femoral head-neck offset was significantly reduced in the lateral-to-anterior aspect of the neck for young men, and in the anterolateral-to-anterior aspect of the neck for older women. For patients suspected of having impingement of the rim, anatomical variations in the proximal femur should be considered as a possible cause.

Femoroacetabular impingement and the cam-effect. A MRI-based quantitative anatomical study of the femoral head-neck offset

We have observed damage to the labrum as a result of repetitive acetabular impingement in non-dysplastic hips, in which the femoral neck appears to abut against the acetabular labrum and a non-spherical femoral head to press against the labrum and adjacent cartilage. In both mechanisms anatomical variations of the proximal femur may be a factor. We have measured the orientation of the femoral neck and the offset of the head at various circumferential positions, using MRI data from volunteers with no osteoarthritic changes on standard radiographs. Compared with the control subjects, paired for gender and age, patients showed a significant reduction in mean femoral anteversion and mean head-neck offset on the anterior aspect of the neck. This was consistent with the site of symptomatic impingement in flexion and internal rotation, and with lesions of the adjacent rim. Furthermore, when stratified for gender and age, and compared with the control group, the mean femoral head-neck offset was significantly reduced in the lateral-to-anterior aspect of the neck for young men, and in the anterolateral-to-anterior aspect of the neck for older women. For patients suspected of having impingement of the rim, anatomical variations in the proximal femur should be considered as a possible cause.

Gluteus minimus-induced femoral head deformation in dysplasia of the hip

Lateral notching of the femoral head is considered pathognomonic for spastic subluxation of the hip. Less frequently, flattening is seen with extrusion of the femoral head in nonspastic hip dysplasia. The aim of this study was to throw light on its underlying pathomechanism. On the radiographs of 297 hips with developmental dysplasia, lateral flattening of the femoral head was seen in 18 hips (6%), but notching was present in only 1. Of 7 dysplasias due to cerebral palsy, 6 showed lateral notching. The gluteus minimus was felt to be responsible for the lateral femoral head changes as the muscle counteracts lateral migration of the femoral head. Intraoperative dissection of 3 hips supported this view. 1 hip with developmental dysplasia and lateral notching was subjected to a periacetabular osteotomy. At surgery, the tendon of the gluteus minimus was found to fit tightly into the notch. Of 2 hips with spastic dysplasia, 1 presented with and the other without lateral notching. In the hip with lateral notching, the gluteus minimus had a normal appearance and it lay in the defect of the femoral head. In the hip without notching, the gluteus minimus was atrophied with signs of fatty degeneration. We therefore believe that lateral notching is a sign of hypertonicity of the gluteus minimus muscle.

Cross-Table Lateral Radiographs for Screening of Anterior Femoral Head-Neck Offset in Patients with Femoro-Acetabular Impingement

One theory for the aetiology of osteoarthrosis of the hip is the impingement of the anterior femoral neck against the acetabulum in flexion. The reduced femoral head-neck offset not visible on AP-radiography is implicated in this impingement. The anterior part of the head-neck region is well visualised on cross table lateral radiographs. A retrospective analysis of the offset using cross table lateral radiographs was therefore performed on twelve symptomatic and ten asymptomatic hips. The anterior offset (AOS) was defined as the difference in radius between the anterior femoral head and the anterior femoral neck. The offset ratio (OSR) was defined as the AOS divided by the femoral head diameter. The AOS was 11.6 ± 0.7 mm in the asymptomatic group and 7.2 ± 0.7 mm in the symptomatic group, which was statistically significantly different (p=0.0006). The OSR was 0.21 ± 0.03 in the asymptomatic group and 0.13 ± 0.05 in the symptomatic group, which was also statistically significantly different (p=0.0004). Cross-table lateral radiographs of the hip are useful for screening patients complaining of anterior femoro-acetabular impingement symptoms, as their anterior femoral head-neck offset may be smaller.

Development of transplanted fetal bones: differences between isografts and allografts in mice

Allogeneic bone from bone banks frequently is used when large skeletal defects have to be bridged in orthopaedic surgery. Beside immunologic rejection of the graft, the loss in osteogenic potential caused by bone banking procedures may be a major reason for limited clinical success. Similar problems as described for bone have occurred with cartilage and osteochondral transplants. Improving the properties of allogenic bone so that its biologic activity becomes comparable to autologous bone could be substantially beneficial for the outcome of allograft transplantation. To dissect the steps involved in the integration of a fetal osteochondral graft as it matures to bone, the current study compared the development and biologic function of metatarsals from 18-day-old fetal mice freshly transplanted in three different immunologic settings. Morphologic assessment of (1) isografts and (2) allografts in nonsensitized hosts 12 days after transplantation revealed that the grafts bear an intrinsic potential to develop after transplantation. In allografts in nonsensitized hosts, however, a slight alteration in biologic activity as compared with isografts could be detected already in this early phase after transplantation by in situ hybridization for messenger ribonucleic acids encoding extracellular matrix proteins. (3) In contrast to isografts and allografts in nonsensitized hosts, morphologic features and biologic function of allografts transplanted to presensitized hosts were altered severely.

[Inadequate detectability of early stages of coxarthrosis with conventional roentgen images]

AIM

The study was undertaken to determine the value of standard radiographs in the early stages of osteoarthritis.

METHODS

Standard radiographs and arthro-MRI's from thirty hips operated on for early arthrosis (age 25-57 years) were independently analyzed by two orthopaedic surgeons and one radiologist blinded from the intra-operative findings. The radiographs were read on two occasions two months apart. The radiographic findings were then compared to the intra-operative findings.

RESULTS

Intra-operatively, all cases had a labral lesion and, in all but three of the cases, there was a major acetabular cartilage lesion. Each investigator diagnosed all of the labral and/or cartilage lesions on the arthro-MRI. However, on average, the investigators judged 20% (10-35%) of the hips to be normal on the standard radiographs. The probability of detecting an abnormal hip joint was statistically significantly better with arthro-MRI in four of six readings (p < 0.05) and there was a trend in favor of the arthro-MRI in the other two readings (p < 0.1). Intra-observer agreement when using the Tönnis classification of arthrosis on standard radiographs was 0.26 (-0.1-0.62), 0.69 (0.42-0.96) and 0.83 (0.53-1) [kappa-statistic, (95% confidence interval)]. The interobserver agreement was 0.24 (-0.07-0.55).

CONCLUSION

Plain radiographs in the early stages of osteoarthrosis of the hip are neither reliable nor valid to diagnose the onset of disease. Therefore, in the case of a normal radiograph and clinical suspicion of arthrosis, a "normal" radiograph does not exclude the diagnosis and an artho-MRI should be obtained for further evaluation.

Rationale of periacetabular osteotomy and background work

The Bernese periacetabular osteotomy is a joint-preserving procedure used after growth plate closure to correct acetabular coverage and stabilize the femoral head. The polygonal, juxta-articular osteotomy respects the vascular blood supply to the acetabular fragment and facilitates an extensive acetabular reorientation. It achieves improvement of the insufficient coverage of the femoral head, reduction of mediolateral displacement, and correction of the version of the fragment. All osteotomies are performed through the modified Smith-Petersen approach, which also allows for an anterior capsulotomy. Joint inspection not only provides information on lesions of the rim but also facilitates the control of an impingement-free range of motion after the correction. The posterior column remains partially intact, allowing minimal internal fixation of the acetabular fragment and early mobilization similar to that after an intertrochanteric osteotomy. Because the majority of this patient population consists of young women, it is important to note that the dimensions of the true pelvis and thus the potential for future vaginal delivery are preserved.

Free nerve endings in the ligamentum capitis femoris

We report the presence of free nerve endings (FNE) in the ligamentum capitis femoris (LCF). Qualitative and quantitative measurements on the incidence of FNE, as assessed by immuno-histochemistry for the S-100 protein, were obtained from 18 patients undergoing hip surgery. We found FNE in all LCF, with no association to age. The presence of FNE in the LCF suggests a role in noci-/proprioception of the hip.

The effect of pedicle artery vasospasm on microhemodynamics in anatomically perfused and extended skin flap tissue

The aim of this study was to evaluate quantitatively the influence of pedicle artery vasospasm on the microcirculation in skin flaps, particularly in the jeopardized extended portions. For this purpose, the hamster island skin flap model was used, which allowed for simultaneous assessment of hemodynamics in both the pedicle artery and the microvasculature of the flap by intravital microscopy. Vasospasm was induced by applying a V3 microvascular clamp for 30 seconds. Clamping resulted in a severe vasospasm, with the artery exhibiting a diameter of 7% +/- 2% (mean +/- standard error) of its original diameter (n = 10; p < 0.01), and with a reduction of total blood flow to the flap of 11% +/- 2% (p < 0.01). Diameter and blood flow recovered gradually to baseline levels after 25 and 15 minutes respectively. During recovery from severe pedicle artery vasospasm (moderate to mild vasospasm), the arterioles in the anatomically perfused flap tissue (n = 38) showed reactive vasodilation (p < 0.01), which was absent in the extended tissue (n = 49; p < 0.01 vs. anatomic). At a pedicle artery vasospasm of 50% of the original diameter, blood flow was restored to normal levels in the anatomically perfused arterioles, but remained below baseline in the extended part (partly p < 0.05 vs. baseline and anatomic). The findings suggest that the development of ischemic necrosis in extended flap portions may be promoted by prolonged, moderate vasospasm, which is well tolerated in the anatomically perfused tissue because of its high capacity for implementing compensatory local regulatory mechanisms.

Slipped capital femoral epiphysis: early mechanical damage to the acetabular cartilage by a prominent femoral metaphysis

On the basis of intraoperative observations in 13 consecutive adolescents (14 hips) with slipped capital femoral epiphysis (SCFE), we found that when the anterior femoral metaphysis was level with or extended past the epiphysis, it caused labrum and cartilage damage. As a result of an impingement between the metaphysis and the superomedial acetabular rim, the labrum revealed erosions, scars or tears. Further jamming of the metaphysis into the joint damaged the adjacent acetabular cartilage, varying from a partial- to a full-thickness cartilage loss. In all patients, the femoral head cartilage was intact; no avascular necrosis was present. Our findings suggest that arthrosis in SCFE can be triggered by early mechanical damage of the acetabular cartilage.

The evolution of indirect reduction techniques for the treatment of fractures

During the last decade, classic AO/ASIF techniques for internal fixation shifted from direct reduction and rigid fixation to biologic internal fixation using indirect reduction techniques. Biologic internal fixation is characterized by the preservation of bone and soft tissue vascularity and relative rather than absolute mechanical stability. Reduction is achieved by using soft tissue traction while obtaining axial and rotational alignment and the correct length. Stabilization is performed when possible by compression plating for load sharing or by bridge plating in comminuted fractures. Advancements of these techniques and the development of newer implants that minimize vascular damage have contributed to the development of biologic internal fixation. By using indirect reduction, by using longer plates to improve the mechanical leverage, and by applying fewer screws to avoid unnecessary damage to the bone, fracture union rates were high. There also was a decreased need for supplemental bone grafting. All of these factors provided stable fixation and allowed early motion.