Introduction

Fretting crevice-corrosion (tribocorrosion) of metallic biomaterials is a major concern in orthopedic, spinal, dental and cardiovascular devices¹. Stainless steel (i.e., 316L SS) is one alloy that sees extensive use in applications where fretting, crevices and corrosion may be present. While fretting-corrosion of this alloy has been somewhat studied, the concept of fretting-initiating crevice corrosion (FICC), where an initial fretting corrosion process leads to ongoing crevice-corrosion without continued fretting, is less understood. This study investigated the susceptibility of 316L SS to FICC and the role of applied potential on the process. The hypothesis is crevice-corrosion can be induced in 316L SS at potentials well below the pitting potential.

Introduction

In hip arthroplasty, it has been shown that assembly of the femoral head onto the stem remains a non-standardized practice and differs between surgeons [1]. Pennock et al. determined by altering mechanical conditions during seating there was a direct effect on the taper strength [2]. Furthermore, Mali et al. demonstrated that components assembled with a lower assembly load had increased fretting currents and micromotion at the taper junction during cyclic testing [3]. This suggests overall performance may be affected by head assembly method. The purpose of this test was to perform controlled bench top studies to determine the influence of impaction force and compliance of support structure (or damping) on the initial stability of the taper junction.

Statement of Purpose

Mechanically assisted crevice corrosion of modular tapers continues to be a concern in total joint replacements as studies have reported increases in local tissue reactions¹. Two surgical factors that may effect taper seating mechanics are seating load magnitude and orientation.

In this study 12/14 modular taper junctions were seated over a range of loads and loading orientations. The goals of this study were to assess the effects of load magnitude and orientation on seating load-displacement mechanics and to correlate these to the pull-off load.

Introduction: The tissue sparing direct anterior approach (DAA/MicroHip) has been developed to improve patients’ rehabilitation and long-term function. But there was no long term evaluation up to now.

The approach is aligned along the interneural plane of Smith-Peterson, with complete preservation of the musculotendinous structures. The femoral neck oeteotomy is performed without dislocation or resection of the joint capsule. Because we perform the DAA without traction table no additional traction was applied to the soft tissues.

Methods: 55 patients underwent traditional THR (lateral approach) surgery In 2003 and 216 consecutive, non selected patients underwent THR with DAA. All Data was recorded prospectively including Haris Hip Score and gate analysis on a treadmill incorporating a dynamic force place. This data is compared to a similar group of patients operated by a traditional Harding approach. No other variables other than the surgical technique were changed for the protocol.

Results: The two groups of patients were comparable in terms of age and BMI. Blood loss dropped by 42%. Hospital stay was reduced by 2.1 days (+/−0.6.) Cup inclination was 45.56 (+/−3.4) in the traditional group and 44.8 (+/−3.7) in the MicroHip group. The dislocation rate was lower in the MicroHip group, being 0.4% compared with 3.5 in the traditional group. Harris Hip score for the MicroHip group was 91.35 (78.3) at 3 months and 94.43 (86.4) at 1 year. At five years there was still a significant difference (p< 0.001) between the two groups.

The gate analyze (excluding all patients with additional joint problems) in 98.8% of the DAA group no significant difference between the operated and the non-operated leg at five years.

Discussion: Even if the DAA a demanding technique for THR and should be used only by high volume surgeons we could prove that there is a significant long-term benefit for the patients. The benefit is certainly higher for high demand patient, but also handicapped patients or very obese patients demonstrate a better outcome. The results indicate that the joint function is more influenced by the soft tissues then by the implant design. But implant design is never the less very important for long term survivorship.

Introduction: Women have gender specific shape of the distal femur. To fit these gender characteristics, gender specific femoral implants were developed for total knee arthroplasty (TKA). We aimed to compare

objective and subjective functional improvement;

Materials and Methods: 30 women (60 knees) operated on successively (6 months in between) for a bilateral TKA between March 2006 and March 2008 by the same surgeon were included in this prospective study. The same surgical protocol and the same post-operative management protocol were applied for both sides. Mean age was 67±3 and mean BMI 26±4 Kg/m². At a minimum follow-up of one year, evaluation objective and subjective functional improvement, patient satisfaction and preference and cost-utility analysis were performed double blind.

Results: Knee Society knee score and Knee Osteoarthritis Outcome Score (KOOS) improvements were comparable in both groups. However, 75% of the women preferred their gender TKA (p< 0.001). 68% of the women described less crepitus or anterior knee bothering after gender TKA (p=0.003) and 64% had faster recovery with the gender implant (p< 0.001). The cost-utility analysis was favorable for the gender knee.

Discussion: No objective or subjective superiority in terms of functional improvement was shown with gender specific implants at this short-term follow-up. However significant differences in terms of patient satisfaction and preference and a favorable cost-utility analysis were observed. These results should now be confirmed at longer-follow-up. Despite comparative functional improvement, patient satisfaction and preference were higher for the side implanted with a gender specific TKA in this prospective comparative study.

Introduction: A new ultra congruent, postero-stabilized total knee arthroplasty (TKA) with a mobile bearing, the FIRST knee prosthesis (Free Insert in Rotation Stabilized in Translation, Symbios SA), was designed and expected to significantly reduce polyethylene wear, to improve the range of motion and the overall stability of the knee while ensuring a physiological ligament balance. Gait analysis has proven to give really objective outcome parameters after lower limb surgery. The goal of our study was to compare the subjective and really objective results of this new TKA with two other widespread models of TKA.

Methods: A clinical prospective monocentric cohort study of 100 consecutive patients (47–88 yrs) undergoing a FIRST TKA for primary osteoarthritis is currently being done. Pre- and post-operative follow-ups (6 weeks, 4 months and 1 year) were done with well-recognized subjective evaluations (EQ-5D and WOMAC scores) and semi-objective questionnaires (KSS score and radiography evaluation) as well as with a really objective evaluation using gait parameters from 6 walking trials, performed at different speeds (slow, normal and fast) with an ambulatory gait analysis system (Physilog^®, BioAGM CH). The outcomes of the first 32 new TKA after one year of follow-up were compared to the results after 1 year of a randomized controlled clinical trial comparing 29 NexGen^® postero-stabilized TKA (Zimmer Inc) with a fixed bearing and 26 NexGen^® TKA with a mobile bearing using the same methods.

Results: Subjective and semi-objective results were similar for the three types of TKA. As for the really objective parameters, the gait cycle time of the FIRST TKA was statistically significantly shorter at normal speed of walk, as well as double-support periods, as compared to both standard models. The extension (in terms of range of motion when walking) of the operated knee was significantly improved for all three types of walk in favour of the FIRST TKAs compared to both NexGen TKAs. The normal walking speed was significantly higher with faster swing speed and stride lengths for the new TKA. Significantly better coordination scores were observed at normal walking speed for the FIRST TKA as compared to the fixed-bearing TKAs.

Conclusion: The FIRST TKAs showed statistically significantly better objective outcomes in terms of gait after one year of follow-up with similar subjective and semi-objective results in comparison with widespread TKA designs. These encouraging short-terms results will have to be confirmed at a 5 years follow-up of the FIRST TKAs.

Purpose: The pisitriquetral articulation can be a source of pain, particularly after trauma. If conservative treatment fails, pisiformectomy appears to be the best alternative. The purpose of this work was to assess clinical and functional outcome after pisiformectomy.

Material and method: Thirteen patients were reviewed 31.5 months (mean) after pisiformectomy. Two patients had a bilateral procedure giving 15 pisiformectomies. Occupation-related trauma was the principal cause. Four patients also had ulnar neuropathy. The same operative technique was used for all patients and a visual analogue scale was used to assess pain.

Results: There were no postoperative complications. At last follow-up, outcome was excellent in twelve cases, good in two and fair in one (n=15). Residual pain was scored a mean 0.8 points versus 6.4 points preoperatively (p< 0.001). Wrist motion was improved after surgery.

Conclusion: There are many causes of pisotriquetral disease, but trauma, or microtraum, predominates. Pisiformectomy is the best treatment after failure or deterioration of results of conservative treatment. It must be remembered however that pisotriquetral disease may be a revealing sign of a regional disorder that must be identified.

Eight children developed osteochondroma (OS) at a mean of 88 months, after hematopoietic stem cell transplantation (HSCT). The mean age at HSCT was 56 months (12-84). This represents a cumulative incidence of 20% among patients less than 18 years of age transplanted from 1981 to 1997. These eight patients underwent allogeneic (n=2) of autologous (n=6) transplantation for either acute leukemia (n=6) or neuroblastoma (n=2) after a conditioning regimen including total body irradiation (n=7) or a combination of Busulfan and Cyclophosphamide.Multiple OS were indentified in seven patients and a solitary OS in one. Locations included: clavicle (2), ribs (2), superior iliac epiphysis (1), metaphy-sis of the distal femur (2), distal (2) and proximal (1) tibia, proximal humerus (1), distal radii (3), scapula (3), proximal metaphysis of the proximal phalanges of the fingers (2) and parietal bone (1). OS were asymptomatic in four children. Eight lesions in five patients were resected and all were benign. No recurrence occured.Four children received growth hormone before diagnosis of OS, but there was no clinical, radiological or histological difference between those who did not. Univariate analysis showed an increased rate associated only with autolo-gous HSCT, with a 31,7% probability of a new OS et 12 years after HSCT.Ostoechondroma should be added to the other adverse effects of HSCT in children.

Purpose: Tibiotalar arthrodesis is a classical procedure for the treatment of painful deformation-destruction of the tibiotalar joint. The purpose of this retrospective study was to determine prognostic factors and tolerance to tibiotalar arthrodesis observed in 68 procedures performed with two different techniques (47 surgical fusions (Group 1), and 21 arthroscopic fusions (Group 2)).

Material and methods: Between 1985 and 1999, 68 patients, mean age 51 years (22–88) underwent 55 arthrodesis procedures (47 post-traumatic, 2 paralytic, 6 rheumatoid polyarthritis, 4 sequelae of septic arthritis). All patients had major functional impairment. The tibiotalar joint was stiff in all cases and mean motion was 20 ± 15°. The subtalar facet was nearly normal in 33 cases, altered in six and had already fused in nine. The mediotarsal facet was altered in 12 cases, six had already had a double arthrodesis, and was normal in 50. On the preoperative Méary view, there was a normal axis in 13 patients, valgus in 28 and varus in 24. According to the Duquennoy radiographic criteria, there was subtalar involvement in 32 cases and mediotarsal involvement in 19. Tibiotalar arthrodeses procedures were performed arthroscopically after 1993 for cases with little axial deformation. Open surgery was used for all other cases (43 Méary technique). A plaster cast was used in all cases. All patients were reviewed using the Duguennoy score and two radiographic views: lateral weight-bearing view for the sagittal plane position (tibiopedious angle) and the Méary view for the frontal plane.

Results: At a mean follow-up of four years, fusion rate was 82% (group 1 83%, group 2 81%). Mean delay to fusion was 3.2 ± 1 month irrespective of the causal disease or surgical technique. Functional outcome was very good in 28%, good in 34.5%, fair in 34.5% and poor in 3% and did not depend on the surgical technique. The subtalar was painful with zero motion in 18 cases (26.5%), generally associated with residual equine. The mediotarsal was stiff in 17 cases and very painful in four. In the frontal plane, 16 ankles were correctly axed, 27 were in valgus (mean 5.6°) and 20 in varus (mean 7.6°) with no difference between the two groups. In the sagittal plane, four ankles were in talus, nine in neutral position, and 49 had a residual equine, including 32 > 5°. In most cases, fair or poor outcome was related to subtalar pain. More than 50% of the patients with equine fusion greater than 5° had subtalar pain.

Conclusion: For the same deformity, arthroscopic arthrodesis can shorten hospital stay and improve the rate and degree of trophic disorders. Arthroscopic tibiotalar arthrodesis is an elegant technique that we use for centred ankles or for patients with risk factors, particularly skin conditions. The rate of fusion with the arthroscopic approach is not however better than with open surgery. Precise clinical and radiological assessment of the subtalar facet as well as the position of the fusion in the sagittal plane at 90° without equine deviation are important prognostic factors observed in this series.