Lucian B. Solomon

Posterolateral transfibular approach to tibial plateau fractures: technique, results, and rationale.

We describe a posterolateral transfibular neck approach to the proximal tibia. This approach was developed as an alternative to the anterolateral approach to the tibial plateau for the treatment of two fracture subtypes: depressed and split depressed fractures in which the comminution and depression are located in the posterior half of the lateral tibial condyle. These fractures have proved particularly difficult to reduce and adequately internally fix through an anterior or anterolateral approach. The approach described in this article exposes the posterolateral aspect of the tibial plateau between the posterior margin of the iliotibial band and the posterior cruciate ligament. The approach allows lateral buttressing of the lateral tibial plateau and may be combined with a simultaneous posteromedial and/or anteromedial approach to the tibial plateau. Critically, the proximal tibial soft tissue envelope and its blood supply are preserved. To date, we have used this approach either alone or in combination with a posteromedial approach for the successful reduction of tibial plateau fractures in eight patients. No complications related to this approach were documented, including no symptoms related to the common peroneal nerve, and all fractures and fibular neck osteotomies healed uneventfully.

Head-Neck Taper Corrosion in Hip Arthroplasty

Modularity at the head-neck junction of the femoral component in THA became popular as a design feature with advantages of decreasing implant inventory and allowing adjustment of leg length, offset, and soft tissue balancing through different head options. The introduction of a new modular interface to femoral stems that were previously monoblock, or nonmodular, comes with the potential for corrosion at the taper junction through mechanically assisted crevice corrosion. The incidence of revision hip arthroplasty is on the rise and along with improved wear properties of polyethylene and ceramic, use of larger femoral head sizes is becoming increasingly popular. Taper corrosion appears to be related to all of its geometric parameters, material combinations, and femoral head size. This review article discusses the pathogenesis, risk factors, clinical assessment, and management of taper corrosion at the head-neck junction.

Anatomy of piriformis, obturator internus and obturator externus: IMPLICATIONS FOR THE POSTERIOR SURGICAL APPROACH TO THE HIP

We dissected 20 cadaver hips in order to investigate the anatomy and excursion of the trochanteric muscles in relation to the posterior approach for total hip replacement. String models of each muscle were created and their excursion measured while the femur was moved between its anatomical position and the dislocated position. The position of the hip was determined by computer navigation. In contrast to previous studies which showed a separate insertion of piriformis and obturator internus, our findings indicated that piriformis inserted onto the superior and anterior margins of the greater trochanter through a conjoint tendon with obturator internus, and had connections to gluteus medius posteriorly. Division of these connections allowed lateral mobilisation of gluteus medius with minimal retraction. Analysis of the excursion of these muscles revealed that positioning the thigh for preparation of the femur through this approach elongated piriformis to a maximum of 182%, obturator internus to 185% and obturator externus to 220% of their resting lengths, which are above the thresholds for rupture of these muscles. Our findings suggested that gluteus medius may be protected from overstretching by release of its connection with the conjoint tendon. In addition, failure to detach piriformis or the obturators during a posterior approach for total hip replacement could potentially produce damage to these muscles because of over-stretching, obturator externus being the most vulnerable.

Posterolateral and anterolateral approaches to unicondylar posterolateral tibial plateau fractures: A comparative study

BACKGROUND Lateral tibial plateau fractures that are located posterolaterally are difficult to reduce through an anterolateral surgical approach because of the lack of direct visualisation of the fracture. This study compared the results of unicondylar posterolateral tibial plateau fractures in two patient cohorts: one treated through a posterolateral direct approach and the other through an anterolateral indirect approach. PATIENTS AND METHODS All nine patients admitted to our hospital, a tertiary care, urban, public hospital in Australia, from 2007 to 2010 with unicondylar posterolateral tibial plateau fractures were treated through a direct posterolateral transfibular approach and prospectively studied. All eight patients admitted from 2004 to 2007 with unicondylar posterolateral tibial plateau fractures were treated through an indirect anterolateral approach and retrospectively reviewed. Fracture reduction and maintenance of reduction were assessed radiographically over 2 years. Knee function was assessed clinically and using the Lysholm score. RESULTS Fractures managed through a direct posterolateral transfibular approach were reduced with no measurable articular step on standard radiography and had no loss of reduction over time. By contrast, fractures treated through an indirect anterolateral approach had a median postoperative articular step of 5.5mm (interquartile range=4.5). These displacements worsened over time in six of the eight patients. At 2 years, patients treated through a direct approach had significantly better Lysholm scores than those treated through an indirect approach. CONCLUSION This study suggests that a direct posterolateral transfibular approach to unicondylar posterolateral tibial plateau fractures results in improved reduction, stabilisation and functional outcomes at early follow-up compared to an indirect anterolateral approach.

Imaging Periprosthetic Osteolysis Around Total Knee Arthroplasties Using a Human Cadaver Model

We examined the sensitivity and accuracy of measuring osteolysis around total knee arthroplasty (TKA) on radiographs, computed tomography (CT), and magnetic resonance imaging (MRI) in a cadaver model. Fifty-four simulated osteolytic defects ranging from 0.7 to 14 cm(3) were created in 6 cadaver knees implanted with either a cemented or an uncemented TKA. Three blinded investigators assessed the presence, location, and volume of defects on radiographs and CT and MRI scans with metal reduction protocols. Both CT and MRI had significantly higher sensitivities and specificities than did plain radiographs (P < .005). Overall, there was no difference in the accuracy of defect volume measurements between CT and MRI (P = .574). This study demonstrates the limitations of radiographs and the high sensitivity and specificity of both CT and MRI in assessing osteolysis around TKA.

The subcristal pelvic external fixator: technique, results, and rationale.

We report a new technique for pelvic external fixation that we have developed as an alternative to the anterosuperior (Slätis) and the anteroinferior (supra-acetabular) type pelvic external fixator configurations. The method principally differs from the other techniques by virtue of the subcristal positioning of the pins and offers advantages in terms of easier pin placement, less skin irritation, less pin tract infection and loosening, and less interference with hip flexion, while allowing dressing, sitting, and walking. Between 1992 and 2006, we successfully used subcristal pelvic external fixators as the definitive fixation device for 20 patients with pelvic ring disruptions. The only complications encountered were superficial pin tract infections in 4 patients (20%) who were successfully treated with wound care and antibiotics.

Weight-bearing-induced displacement and migration over time of fracture fragments following split depression fractures of the lateral tibial plateau: A CASE SERIES WITH RADIOSTEREOMETRIC ANALYSIS

We investigated the stability of seven Schatzker type II fractures of the lateral tibial plateau treated by subchondral screws and a buttress plate followed by immediate partial weight-bearing. In order to assess the stability of the fracture, weight-bearing inducible displacements of the fracture fragments and their migration over a one-year period were measured by differentially loaded radiostereometric analysis and standard radiostereometric analysis, respectively. The mean inducible craniocaudal fracture fragment displacements measured -0.30 mm (-0.73 to 0.02) at two weeks and 0.00 mm (-0.12 to 0.15) at 52 weeks. All inducible displacements were elastic in nature under all loads at each examination during follow-up. At one year, the mean craniocaudal migration of the fracture fragments was -0.34 mm (-1.64 to 1.51). Using radiostereometric methods, this case series has shown that in the Schatzker type II fractures investigated, internal fixation with subchondral screws and a buttress plate provided adequate stability to allow immediate post-operative partial weight-bearing, without harmful consequences.

Wear of highly crosslinked polyethylene acetabular components A review of RSA studies

Background and purpose — Wear rates of highly crosslinked polyethylene (XLPE) acetabular components have varied considerably between different published studies. This variation is in part due to the different techniques used to measure wear and to the errors inherent in measuring the relatively low amounts of wear in XLPE bearings. We undertook a scoping review of studies that have examined the in vivo wear of XLPE acetabular components using the most sensitive method available, radiostereometric analysis (RSA). Methods — A systematic search of the PubMed, Scopus, and Cochrane databases was performed to identify published studies in which RSA was used to measure wear of XLPE components in primary total hip arthroplasty (THA). Results — 18 publications examined 12 primary THA cohorts, comprising only 260 THAs at 2–10 years of follow-up. The mean or median proximal wear rate reported ranged from 0.00 to 0.06 mm/year. However, differences in the manner in which wear was determined made it difficult to compare some studies. Furthermore, differences in RSA methodology between studies, such as the use of supine or standing radiographs and the use of beaded or unbeaded reference segments, may limit future meta-analyses examining the effect of patient and implant variables on wear rates. Interpretation — This scoping review confirmed the low wear rates of XLPE in THA, as measured by RSA. We make recommendations to enhance the standardization of reporting of RSA wear results, which will facilitate early identification of poorly performing implants and enable a better understanding of the effects of surgical and patient factors on wear.

Anatomical study of the ankle with view to the anterior arthroscopic portals

This article evaluates the risk of interference with the neurovascular structures in the four anterior ankle arthroscopic portals, described on each side of the extensor tendons: anteromedial, medial midline, anterocentral and anterolateral. Complications after ankle arthroscopies have been described in up to 17%, most being neurovascular. To quantify the neurovascular risks we dissected 68 cadaveric feet and evaluated the correlations between tendons, vessels and nerves. The mean distance between tibialis anterior and extensor hallucis longus and between extensor hallucis longus and extensor digitorum longus is 4 mm, but in 10–20% these tendons are in apposition or are overlapped. The tibialis anterior vascular bundle was absent in 11.8%, was located between the tibialis anterior and the extensor hallucis longus in 3% and between the extensor hallucis longus and the extensor digitorum longus in 64.7%. A peroneal vascular bundle or branches of the tibialis anterior vascular bundle were located lateral to the extensor digitorum longus/peroneus tertius tendon in 88.2%. Transverse vascular branches were identified in 41.2% over the medial side of the joint line and in 52.9% over the lateral side. The deep peroneal nerve was located between the extensor hallucis longus and the extensor digitorum longus tendons in 58.8%. The superficial peroneal nerve had branches located between the tibialis anterior and the extensor hallucis longus tendons in 2.9%, between the extensor hallucis longus and the extensor digitorum longus tendons in 23.5% and lateral to the extensor digitorum longus/peroneus tertius tendon in 32.4%. These results show that the anteromedial and medial midline portals are the safest. The anterolateral portal should be noted not only for the risks to the superficial peroneal nerve, but also to the peroneal vessels.

Validity and Reliability of the Paprosky Acetabular Defect Classification

BackgroundThe Paprosky acetabular defect classification is widely used but has not been appropriately validated. Reliability of the Paprosky system has not been evaluated in combination with standardized techniques of measurement and scoring.Questions/purposesThis study evaluated the reliability, teachability, and validity of the Paprosky acetabular defect classification.MethodsPreoperative radiographs from a random sample of 83 patients undergoing 85 acetabular revisions were classified by four observers, and their classifications were compared with quantitative intraoperative measurements. Teachability of the classification scheme was tested by dividing the four observers into two groups. The observers in Group 1 underwent three teaching sessions; those in Group 2 underwent one session and the influence of teaching on the accuracy of their classifications was ascertained.ResultsRadiographic evaluation showed statistically significant relationships with intraoperative measurements of anterior, medial, and superior acetabular defect sizes. Interobserver reliability improved substantially after teaching and did not improve without it. The weighted kappa coefficient went from 0.56 at Occasion 1 to 0.79 after three teaching sessions in Group 1 observers, and from 0.49 to 0.65 after one teaching session in Group 2 observers.ConclusionsThe Paprosky system is valid and shows good reliability when combined with standardized definitions of radiographic landmarks and a structured analysis.Level of EvidenceLevel II, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.