Intraprosthetic dislocation: a potentially serious complication of dual mobility acetabular cups.

Though dual mobility cups have gained growing popularity as a solution for instability in total hip replacements, these promising devices are subject to a specific implant failure mode, named intraprosthetic dislocation. We present the case of a patient sustaining such an adverse event. The planned revision surgery was postponed 12 months due to a severe heart condition, allowing a rare opportunity to document the natural history of this unusual complication. The small femoral head was found dislodged in the superior part of the metallic shell and had remarkably lost its sphericity. Severe metallic debris and granuloma were found in the proximal femoral region, associated with major periprosthetic bony and soft tissue damage. Surgeons, radiologists, and general practitioners should be aware of this specific complication, its incidence (almost 5%) and mechanisms (femoral neck to mobile polyethylene insert impingement, leading to rim fatigue and wear of the insert at the capturing area). Diagnosis is mainly based on anteroposterior and modified Lowenstein lateral radiographs of the hip, as an eccentric position of the small femoral head, lying against the concave inner surface of the shell. Prompt component revision should be planned, since delayed management could lead to severe irretrievable damages.

Charnley-Kerboull total hip arthroplasty combining zirconia on polyethylene. A minimum eight-year follow-up prospective study.

PURPOSE: Zirconia was introduced in the 1980s for total hip arthroplasty (THA) with the expectation of lower polyethylene wear. The purpose of this prospective study was to evaluate the results of a continuous series of total hip arthroplasties combining a zirconia head with polyethylene socket at a minimum eight-year follow-up. METHODS: We performed an open prospective clinical trial in 1997. Our study involved 51 consecutive patients (55 hips) with a mean age of 52.5 ± 12 years (range, 25-76 years). All patients had a Charnley-Kerboull all-cemented hip replacement. A 22-mm stabilised yttrium tetragonal polycrystalline zirconia head (Y-TZP) was used in association with moderately cross-linked and annealed polyethylene. Clinical and radiological outcomes were assessed yearly. A survival analysis was performed using revision for any reason as the end-point. RESULTS: At a minimum eight-year follow-up, 12 patients (13 hips) were lost to follow-up (mean 26.8 months), two patients (two hips) had died, and six patients (six hips) were revised. The remaining 31 patients (34 hips) were alive and had not been revised on either the femoral or acetabular side at a mean follow-up of 117.1 months (range, 96-150 months). Mean functional score at last follow-up was 17.7. Mean linear head penetration was 0.23 mm/year. More than 90% of the remaining hips had signs of periprosthetic osteolysis. Five stems were loosened. The survival at eight years was 87.3% (95% IC: 76.7-97.8). CONCLUSION: This study confirms earlier short-terms results, and demonstrates that zirconia should no longer be used in THA.

Is percutaneous adductor tenotomy as effective and safe as the open procedure?

BACKGROUND: Percutaneous adductor longus tenotomy (PAT) is a frequently used procedure, yet no study has ever compared its effectiveness and safety with those of open adductor longus tenotomy (OAT). We conducted this prospective study to describe the effects of PAT and to compare them with those of OAT. METHODS: This consisted of a cross-over randomized controlled trial including 50 consecutive hips from 27 patients with cerebral palsy scheduled for adductor tenotomy in the setting of multilevel tendon lengthening/release procedures or hip surgery (femoral or Dega osteotomy) in a university hospital. A pediatric orthopaedic surgeon conducted a PAT. Another surgeon extended the wound to explore what had been cut during the PAT, and completed the tenotomy if necessary. Hip abduction (HA) was assessed by a third surgeon immediately before PAT, after PAT, and then after OAT, using a goniometer, in a standardized reproducible manner. All 3 surgeons were blinded to the others' findings. Primary end-points included the percentage of tendon/muscle portion sectioned percutaneously, and the HA measure. Comparison between HA after PAT and OAT was done using a paired t-test with a 95% confidence interval. The influence of anatomic variants of adductor longus origin was also assessed. RESULTS: Mean HA (hips flexed) measured 40.36 degrees preoperatively and increased to 50.04 degrees after PAT (P<0.0001). After OAT, HA averaged 53.32 degrees with no statistical gain compared with that observed after PAT (P=0.2). The tendinous portion of adductor longus was cut to an average of 98% by PAT (completely in 46 cases and more than 75% in only 4 cases). The muscular portion of adductor longus origin was cut to an average of 83.7% (completely in only 15 cases, cut to more than 75% in 26 cases, and approximately 50% in 9 cases). The gain in HA positively correlated with the extent of the tendinous portion divided (P=0.03) but not with the extent of muscular portion divided. Results were independent of the anatomic variants of adductor longus origin. Partial section of adductor brevis after PAT was encountered in 6 cases. No major iatrogenic lesion was observed (obturator nerve, major vessels). CONCLUSIONS: This is the only prospective study concerning the effects of PAT. The anatomic factor associated with gain in HA seems to be the extent of the section of the tendinous portion of adductor longus origin, which was found to be cut to more than 90% in all cases after PAT. The extent of muscular portion section does not seem to influence the gain in HA. The researchers detail the technique of percutaneous adductor tenotomy and show that when done correctly, PAT is a fast and simple procedure, as reliable and effective as the open release and without any major risks. LEVEL OF EVIDENCE: Level II therapeutic study-prospective comparative study.

Risk of recurrent dislocation and avascular necrosis after proximal femoral varus osteotomy in children with cerebral palsy.

A retrospective review was conducted on 50 children with cerebral palsy, having 89 femoral varus osteotomy at an average age of 7.4 years, trying to identify risk factors for complications, particularly redislocation and avascular necrosis. Among the well-reduced hips, new subluxation developed in 12 cases; postoperative radiographic measurements showed a mean neck-shaft angle of 135 degrees and an acetabular slope of 32 degrees . Main risk factors for secondary dislocation seem to be insufficient correction of preexisting valgus and uncorrected acetabular dysplasia. Avascular necrosis was observed in 33 hips (37%): 26 minor and seven severe. Older age at surgery and high preoperative Reimer's migration index seem statistically significant risk factors.

Is visual estimation of passive range of motion in the pediatric lower limb valid and reliable?

BACKGROUND: Visual estimation (VE) is an essential tool for evaluation of range of motion. Few papers discussed its validity in children orthopedics' practice. The purpose of our study was to assess validity and reliability of VE for passive range of motions (PROMs) of children's lower limbs. METHODS: Fifty typically developing children (100 lower limbs) were examined. Visual estimations for PROMs of hip (flexion, adduction, abduction, internal and external rotations), knee (flexion and popliteal angle) and ankle (dorsiflexion and plantarflexion) were made by a pediatric orthopaedic surgeon (POS) and a 5th year resident in orthopaedics. A last year medical student did goniometric measurements. Three weeks later, same measurements were performed to assess reliability of visual estimation for each examiner. RESULTS: Visual estimations of the POS were highly reliable for hip flexion, hip rotations and popliteal angle (rhoc >or= 0.8). Reliability was good for hip abduction, knee flexion, ankle dorsiflexion and plantarflexion (rhoc >or= 0.7) but poor for hip adduction (rhoc = 0.5). Reproducibility for all PROMs was verified. Resident's VE showed high reliability (rhoc >or= 0.8) for hip flexion and popliteal angle. Good correlation was found for hip rotations and knee flexion (rhoc >or= 0.7). Poor results were obtained for ankle PROMs (rhoc < 0.6) as well as hip adduction and abduction, the results of which not being reproducible. Influence of experience was clearly demonstrated for PROMs of hip rotations, adduction and abduction as well as ankle plantarflexion. CONCLUSION: Accuracy of VE of passive hip flexion and knee PROMs is high regardless of the examiner's experience. Same accuracy can be found for hip rotations and abduction whenever VE is performed by an experienced examiner. Goniometric evaluation is recommended for passive hip adduction and for ankle PROMs.

Radiofrequency application to the growth plate in the rabbit: a new potential approach to epiphysiodesis.

BACKGROUND: Radiofrequency energy is being used more and more frequently in orthopaedics, mainly in the treatment of bone tumors. We postulated that radiofrequency ablation may produce growth plate lesions similar to those observed in the bone and conducted this study to see whether radiofrequency may be used as a technique for producing epiphysiodesis. METHODS: We randomized 60 8-week-old female New Zealand white rabbits into 3 groups. Group A was destined for a total epiphysiodesis at 60 degrees C, group B was destined for a total epiphysiodesis at 90 degrees C, and group C for a lateral hemiepiphysiodesis at 90 degrees C. Radiofrequency energy was delivered in 1 minute in all 3 groups. Using fluoroscopic imaging, radiofrequency was applied percutaneously to the left proximal tibial physis whereas the right growth plate received a sham procedure. A bicortical pin was used to evaluate the longitudinal growth rate at every monthly radiologic control, beginning 8 weeks after the procedure. Comparisons between the right and left side and between groups A and B were achieved using a paired t test. A histopathologic study was conducted in parallel to the radiographic study. RESULTS: In a radiograph at the 8-week point, pin migration was 4.74 mm on the left side compared with 9.72 mm on the right (P<0.0001), in group A. In group B, pin migration on the left was 1.37 mm compared with 5.49 mm on the right (P<0.0001). In group C, mean angular deviation was 11.6 degrees on the left compared with 1.9 degrees on the right (P=0.0001). These differences were maintained until the end of growth. Pathology specimens revealed cellular anarchy, loss of columnar stratification, and height of the physis on the left side, which occurred earlier and were more pronounced in group B than in group A. In group C, these changes involved only the lateral half of the left physis whereas its medial counterpart remained normal. There was no evidence of articular cartilage damage. CONCLUSIONS: This experimental study shows that radiofrequency can efficiently and rapidly achieve epiphysiodesis. It is one of many methods that can be used for this purpose. The development of new electrodes suitable for use on human growth plates and the elaboration of specific utilization protocols may lead to its use in children. Its simplicity and precision may lead to a quick and efficient growth arrest with little pain and postoperative disability in addition to reduced costs. CLINICAL RELEVANCE: Radiofrequency has proved to be effective in producing growth arrest in rabbits with no complications. Technical improvements and adaptations may allow its use for pediatric limb inequalities or angular deformities in the near future.

Free vascularized fibular flap for congenital ulnar pseudarthrosis: a report of two cases and review of the literature.

Congenital pseudarthrosis of the ulna (CPU) is an extremely rare disorder that has been treated with various traditional methods with poor results on long-term deformity correction and bony union. Free vascularized fibular grafting (FVFG) has been used to treat congenital pseudarthroses with improved success rates. We report herein 2 cases of CPU treated with FVFG in which bone union was obtained without major difficulty. The distal ulnar hypoplastic physis and epiphysis were spared during excision of the pseudarthrosis in both cases leading to continuous ulnar growth following bone healing. The main challenge concerned the stability of the radiocapitellar joint. There was no complication at the donor site. Free vascularized fibula is a safe and effective method for the treatment of congenital pseudarthrosis of the ulna.

Skeletal features of primary hyperoxaluria type 1, revisited.

PURPOSE: The purpose of this study was to describe the skeletal manifestations of primary hyperoxaluria type 1 (PH1), the most common of the primary hyperoxalurias. METHODS: We clinically and radiographically reviewed 12 consecutive patients diagnosed with PH1, aged between 2 and 17 years. All patients had evidence of some type of renal involvement, 4 of whom were at end-stage renal disease (ESRD) and were under dialysis. RESULTS: The main symptom was skeletal pain and was present only in the 4 severely involved patients and appeared during the second year of dialysis. The 2 most severely involved patients had evidence of pathological fractures. Radiological signs were present in patients with or without symptoms. These radiological signs were of two distinct types: those almost specific of oxalosis, such as dense and radiolucent metaphyseal bands and vertebral osteocondensations, which are found mainly in the severely involved individuals, and those less specific, such as signs of renal osteodystrophy, which are also found in less severely involved patients. Interestingly, our study revealed the presence of spondylolysis in 25% of cases. This latter finding is unique and has not previously been reported in the literature. CONCLUSIONS: The skeletal manifestations of PH1 include specific and less specific radiological signs, with some patients being asymptomatic, and others presenting with bone pain and pathological fractures, as well as spondylolysis.

Pediatric cervical spine instability.

Cervical spine instability in children is rare but not exceptional and may be due to many factors. Although it mostly occurs at the upper cervical spine, all vertebrae from the occiput to T1 may be involved. It may be acute or chronic, occurring secondary to trauma or due to congenital anomaly, skeletal or metabolic dystrophy or rheumatoid arthritis. It can be isolated or associated with other musculoskeletal or visceral anomalies. A thorough knowledge of embryology, anatomy, physiology and physiopathology of the cervical spine in children is essential to avoid pitfalls, recognize normal variants and identify children at risk of developing cervical spine instability and undertake the appropriate treatment.

The risk of neuro-orthopaedic malformations following in-vitro fertilization.

The purpose of this study was to assess the risk of neuro-orthopaedic malformations after in-vitro fertilization. We compared the prevalence of neuro-orthopaedic malformations in two groups of pregnancies conceived either naturally or by in-vitro fertilization, and used multivariate analysis to study the impact of each variable. The results showed a prevalence of 0.89% neuro-orthopaedic malformations in the in-vitro fertilization cohort and 0.32% in the natural conception cohort. The three times greater risk of malformations in the in-vitro fertilization cohort was reduced after adjustment to other variables. We concluded that the increased risk of neuro-orthopaedic malformations after in-vitro fertilization is not due to the technique itself but rather to factors associated with it.