Camdon Fary

Tibial component rotation assessment using CT scan in medial and lateral unicompartmental knee arthroplasty.

BACKGROUND Rotation of tibial component has not been analysed in literature for unicompartmental knee arthroplasty. The purpose of the study was to determine and compare the rotation of medial and lateral unicompartmental knee arthroplasty (UKA) tibial components. We assumed both components (lateral and medial) were positioned with external rotation. PATIENTS AND METHODS Eighteen lateral and 19 medial UKA patients were scanned postoperatively in neutral position with computed tomography enabling lower extremity three-dimensional image acquisition from the hip to the ankle. All the patients were operated by three different senior surgeons using the same surgical technique. From the reconstructions we measured the two-dimensional (2D) rotation of the tibial components. RESULTS The rotation of the tibial component was external (mean 6.5°, SD 5.1°) for the medial UKA and external (mean 7.3°, SD 10.3°) as well for the lateral UKA. The difference was statistically insignificant (P=0.717). DISCUSSION This study presents the first 2D in vivo analysis accurately determining and comparing medial and lateral UKA component rotation. Despite a wide range of value, we found both components were indeed externally rotated. The variability in implant positioning was observed despite the rigorous performance of an experienced surgeon using routine techniques in patients selected under routine criteria. Further analysis of these patients for satisfaction and implant survivorship in relation to implant rotation may give us an optimal range for the tibial component. If it is found that this ideal range cannot be consistently obtained with current surgical techniques then there may be a case for the use of a navigation system.

5- to 16-year follow-up of 54 consecutive lateral unicondylar knee arthroplasties with a fixed-all polyethylene bearing.

The clinical and radiographic results of 54 knees (52 patients) with a unicondylar knee arthroplasty (UKA) with fixed-all polyethylene bearing implanted for lateral osteoarthritis were studied at 5- to 16-year follow-up (mean, 100.9 months). Four underwent second surgery: 1 conversion to total knee arthroplasty and 3 received UKA in the medial compartment. The mean International Knee Society knee score was 94.9 points, with a mean range of motion of 132.6° and a mean International Knee Society function score totaling 81.8 points. Implant survival was 98.08% at 10 years. These excellent results suggest that UKA with fixed-all polyethylene bearing is a reliable option for management of isolated lateral knee osteoarthritis.

Does a Collar Improve the Immediate Stability of Uncemented Femoral Hip Stems in Total Hip Arthroplasty? A Bilateral Comparative Cadaver Study

The aim of this study was to compare the immediate stability of collared vs collarless uncemented femoral stems in total hip arthroplasty. A bilateral comparative study of 20 cadavers (40 hips: 20 collarless, 20 collared) was performed. Forces in the vertical and horizontal planes required to initiate subsidence of femoral stem and subsequent femoral fracture were measured. In vertical plane, subsidence began at an average force of 3129 ± 494 N for collarless stems and 6283 ± 3584 N for collared stems (P = .02). Fracture occurred at a significantly higher force for collared stems (P = <.001). In horizontal plane, subsidence began at an average force of 540 ± 170 N for collarless stems and 678 ± 206 N for collared stems (P = .01). Fracture occurred at a significantly higher force for collared stems (P = .005). Collared uncemented stems have significantly greater immediate stability than collarless. They are able to withstand greater vertical and horizontal forces before the initiation of subsidence and subsequent fracture.

Treatment of chronic disruption of the patellar tendon in Osteogenesis Imperfecta with allograft reconstruction

We present a case of chronic disruption of the patellar tendon in a patient with Osteogenesis Imperfecta. This patient was treated with a customized extensor mechanism allograft. Results were excellent at 5 years follow up. To our knowledge this treatment has not previously been published in this situation. We present this as a reliable treatment option.

Total hip arthroplasty using direct anterior approach and dual mobility cup: safe and efficient strategy against post-operative dislocation

AimWe hypothesize that a dual mobility cup can be safely used via the direct anterior approach, without increasing the risk of complications or incorrect positioning.Materials and methodsThis retrospective study compared 201 primary total hip arthroplasties using a dual mobility cup performed via direct anterior approach without a traction table, to 101 arthroplasties performed via posterolateral approach. Implant positioning, function scores, and early complications were recorded.ResultsImplant positioning was appropriate in both groups, with a higher cup anteversion in direct anterior approach. The complications rates were similar in both groups, with no dislocation or infection.ConclusionThe direct anterior approach without traction table associated with a dual mobility cup does not increase the risk of complications or non-optimal positioning of implants. This strategy is interesting for patients with high risk of post-operative dislocation.

The evolution of outcomes and indications for the dual-mobility cup: a systematic review

PurposeInstability following total hip arthroplasty remains a common and disabling complication. The dual mobility cup (DMC) allows a reduction in the dislocation rate. An increasing number of studies have been undertaken to better understand DMC long term outcomes and complications. The goal of this systematic review was to clarify its different uses and outcomes according to the indications.MethodsA comprehensive literature review was performed using the keywords ‘dual mobility’ and ‘tripolar cup’ with no limit regarding the year of publication. One hundred seventy six publications were identified.ResultsCurrent literature shows that “contemporary” dual mobility cup are a significant indication to manage instability following primary and revision hip arthroplasty. Survivorship at midterm is comparable to other articulations for primary THA, but is more difficult to evaluate in revision. Intra-prosthetic dislocation, wear, and loosening are now uncommon with new generations of DMC.ConclusionsCompared to previous generations of DMC, the current “contemporary” DMC presents a significant improvement. Current literature reveals a tendency to increase the indications but further studies with long term follow up remain important to consolidate these findings.

The Corail ® Hip Stem

Corail® implants suit most femoral anatomies (Dorr-types A, B and C). Nevertheless, in all cases the indications need to be planned carefully taking account of the specifi c demands of the individual patient. It is important for the surgeon to understand the principle of ‘compaction broaching’ and the mechanism of fi xation using a fully hydroxyapatite-coated (HAC) stem as well as the correct implantation technique in order to achieve the best possible result for all patients. Even then, the surgeon needs to be aware that there might be some rare situations in which a different surgical technique is needed.

Influence of femoral broach shape on stem alignment using anterior approach for total hip arthroplasty: A radiologic comparative study of 3 different stems

Background Malalignment of the femoral stem in total hip arthroplasty (THA) can detrimentally affect outcome. Poor preparation of the femur intraoperatively is an important cause of stem malalignment. Purposes The objective was to compare coronal alignment of three different stems using three different broaches. Methods Retrospective study of three groups of 60 patients following primary THA via direct anterior approach, by the same surgeon, between January 2015 and January 2016. Each group had a similar designed stem (Corail Depuy, Targos Lepine or Meije Tornier). Groups were matched for age, body mass index, gender, side, neck shaft angle and indications. The significant difference between groups was the broach shape. Broaches for the Corail and Meije stems had a prominent shoulder laterally, while the broach of the Targos stem had a rounded less prominent shape laterally. Coronal alignment was determined radiologically at 2 months. Results The mean varus was significantly lower for the Targos stems (1.1° +/-0.8) compared to the Corail (2.3° +/-1.5) and Meije stems (1.9° +/-1.2) (p<0.0001). There were significantly less Targos stems with varus greater than 3° (1.7%, n = 1) compared to the Corail (40%, n = 24) and Meije stems (20%, n = 12) (p<0.001). Conclusion A femoral broach with a prominent lateral shoulder when performing a THA via direct anterior approach will increase the risk of varus femoral stem alignment compared to a less laterally prominent broach.