The use of polymethyl methacrylate based cement for the fixation of joint replacements although commonly applied, is still limited by interfacial weakness. This study aims to document the effects of a variety of surface treatments on implant/cement bonding and link them to their surface properties. Thirty seven femoral implant analogues of Ti6Al4V rods were given one of six different surface treatments: traditional grit blasting, wet and dry Vaquasheening, acid etching in concentrated sulphuric and hydrochloric acid, anodisation at 150V, and a combination of acid etching and anodisation, before being embedded into a commercially available poly(methyl methacrylate) bone cement. The interfacial strength, energy and stiffness were measured through pushout testing. Surface analysis included examination with scanning electron microscopy, wettability tests and roughness analysis. Results were analysed with a one-way ANOVA with post hoc tests. Overall, the coarse blasted surface created the strongest interface, followed by both etched then anodised, acid etched only, wet Vaquasheened, anodised only and finally dry vaquasheened. While anodised samples showed a weaker bond than etched samples, the combination of etching and anodisation was not different to etching alone. In addition, six different types of interface failure modes were observed, and theories as to explain their mechanism, using experimental evidence were outlined. Coarse blasted surfaces showed the strongest bonding, while other surface modifications may encourage tissue ingrowth and other biological responses, these surface treatments do not strengthen bonding for cemented fixation.
Surgical training is based on an apprenticeship model. This training can be divided broadly into three main categories: practical skills, knowledge and decision making. The operating room is the nexus of a large part of surgical teaching. The supervising surgeon imparts both practical teaching as well as didactic information to the trainee during surgical procedures. A large amount of decision making skills are also acquired in the OR. Indeed, a large part of the surgical teams time is spent in the operating room which makes it an ideal educational environment. Bench model training is one teaching modality whereby the novice surgeon is taught surgical skills on life-like models. This practice enhances and accelerates the ability of the trainee to acquire fundamental, technical and surgical skills in the operating room. Whether bench model training provides an advantage on the ability of the trainee to acquire knowledge and decision making skills is unknown. Based on the motor learning theories, it is hypothesized that bench-model training will allow junior residents to be more interactive than trainees lacking similar active hands-on training. In this study, we examined whether bench model training provides an advantage on the ability of the trainee to acquire knowledge and decision making skills. 30 junior surgical residents from various surgical divisions, with minimal knowledge of technical, procedural and cognitive skills related to the ulna bone fixation (primary task), were recruited in this study. 15 residents, randomly assigned, were given instructions and the benefit of practice on a bench model, and 15 were given instructions but not the chance to practice the skill on a bench model. All residents, while tested for their accuracy and time taken for ulna fixation (secondary task, decision making skills), were also verbally taught information on different aspects of primary bone healing. This information was evaluated by a multiple-choice test (knowledge acquisition).Purpose
Method
A total of 12 epileptic patients (14 shoulders)
with recurrent seizures and anterior dislocations of the shoulder underwent
a Latarjet procedure and were reviewed at a mean of 8.3 years (1
to 20) post-operatively. Mean forward flexion decreased from 165° (100° to 180°)
to 160° (90° to 180°) (p = 0.5) and mean external rotation from 54° (10° to 90°)
to 43° (5° to 75°) (p = 0.058). The mean Rowe score was 76 (35 to
100) at the final follow-up. Radiologically, all shoulders showed
a glenoid-rim defect and Hill-Sachs lesions pre-operatively. Osteo-arthritic changes
of the glenohumeral joint were observed in five shoulders (36%)
pre-operatively and in eight shoulders (57%) post-operatively.
Re-dislocation during a seizure occurred in six shoulders (43%).
Five of these patients underwent revision surgery using a bone buttress
from the iliac crest and two of these patients re-dislocated due
to a new seizure. Due to the unacceptably high rate of re-dislocation after surgery
in these patients, the most important means of reducing the incidence
of further dislocation is the medical management of the seizures.
The Latarjet procedure should be reserved for the well-controlled
patient with epilepsy who has recurrent anterior dislocation of
the shoulder during activities of daily living.
In this report, porous tantalum was used to achieve abductor tendon reattachment to structural allograft of the proximal femur in salvage reconstruction of a failed total hip arthroplasty. In each case, a porous tantalum segment with trapezoidal cross section was fixed to a dovetail joint of complementary geometry cut into the lateral greater trochanter. Fixation of the porous tantalum to the allograft was supplemented with polymethylmethacrylate cement. Residual abductors were mobilized from the surrounding soft tissues and secured against the porous tantalum segment with a short greater trochanteric reattachment device and cables. Patients were followed up at 73 and 80 months. Harris Hip Scores of 74 and 80 respectively were found. Both were unlimited community ambulators without support, had negative Trendelenberg signs, and were satisfied with the clinical outcomes. This preliminary experience suggests that porous tantalum has potential application in cases of severe proximal femoral bone loss involving abductor deficiency.
Although soft tissue capsulolabral repairs are the mainstay of treatment for recurrent anterior shoulder instability, bone defects are becoming more commonly recognized as additional problems for these patients. Humeral Head defects have been commonly ignored, however, there are a group of patients with failed procedures who have this as their main pathology. The purpose of this paper is to present a review of patients with large Humeral Head impression defects with a large structural irradiated Allograft. From April 1995 to January 2001, eighteen patients with recurrent anterior shoulder instability with Large Humeral Head Defects (>
25%) were treated with irradiated humeral allografts. Patients underwent physical and radiographic examination, subjective assessments including VAS scores for pain, instability, and satisfaction and completed a Constant and WOSI scores to determine clinical result. Radiograhic evaluation included standard radiographs and either MR or CT assessment. Eighteen Patients with an average age of 31.5 (18–52) were reviewed at an average time of fifty months (24–96) following their surgical procedure. There were fourteen male and four female patients each having had an average of 2.1 (1–8) prior operative procedures. All patients had resolution of their instability with no documented recurrences. All patients had severe apprehension preop and this resolved completely in fifteen. Average loss of external rotation was forty degrees preop and improved to ten degrees postop. Two patients had partial collapse of the graft with symptoms of pain in External Rotation requiring screw removal. There were no other complications. Patients improved on WOSI from 1882 to 381 and had an avearage Constant score of eighty-seven postop. Subjectively all patients would have the procedure again and pain improved from 72.5 to 22.5. There are certain situations where large humeral head defects contribute to the failure of instability repairs and ongoing instability. Allograft reconstruction with matched irradiated grafts is an excellent alternative for eliminating instability.
