Background

Exeter Trauma Stem (ETS) is a polished tapered collarless monopolar prosthesis used for cemented hemiarthroplasty for fracture neck of femur. Two modular rasps are available on the instrumentation set. The larger rasp, in practice, rarely fits into the femur making trial reduction impossible. Our hypothesis was that the absence of a trial reduction could affect leg length and stability of the prosthesis.

Two-stage revisions for the infected THA are associated with lower re-infection rates than directexchange (one-stage) revisions, and for this reason are favored in the U.S. However, the twostage approach may result in increased, but poorly quantified, surgical morbidity. We developed a decision analysis to compare direct-exchange revision to the two-stage approach for treating the infected THA.

We performed a systematic literature search for papers that analyzed direct-and two-stage revisions for the treatment of chronic infections after THA, with a > 2 years follow-up. This provided frequencies of the most common postoperative (interim and final) health states. These were converted to monthly probabilities to permit decision analysis. We conducted and previously published two surveys to obtain utility values, one in experienced arthroplasty surgeons and another in patients. Using those probabilities and utilities, we created a Markov cohort modeling the postoperative health states seen during treatment of the infected THA.

Sensitivity analysis was performed for each variable in the tree to verify the models robustness.

Using a 12-month cycle, the Markov model favored direct-exchange revision over the twostage approach, regardless of whether surgeon-or patient-derived utilities were used (0.941 vs. 0.642 expected value (EV), and 0.889 vs. 0.551 EV, for patient-and surgeon-derived utilities, respectively; p< 0.01). These findings were also significant in a lifetime model with a ten-year life expectancy (p< 0.01). The findings were robust in sensitivity analyses using a clinically salient range of input variables.

This decision analysis, which used a systematic review of the literature (for complication and outcome frequencies) and published study-specific survey data from patients and experienced surgeons (for utility values of those health states) found direct-exchange arthroplasty to be superior to the two-stage revision for treating the infected THA. This finding was unexpected, in that this is not our typical approach nor is it favored in this country.

After obtaining informed consent, 80 patients were randomised to undergo a navigated or conventional total knee replacement. All received a cemented, unconstrained, cruciate-retaining implant with a rotating platform. Full-length standing and lateral radiographs and CT scans of the hip, knee and ankle joint were carried out five to seven days after operation.

No notable differences were found between computer-assisted navigation and conventional implantation techniques as regards the rotational alignment of the femoral or tibial components. Although the deviation from the transepicondylar axis was relatively low, there was a considerable range of deviation for the tibial rotational alignment. There was no statistically significant difference regarding the occurrence pattern of outliers in mechanical malalignment but the number of outliers was reduced in the navigated group.

Aims: To clarify whether joint loading after meniscus repair causes increased pressure on the femoral condyle and is responsible for early cartilage damage. Methods: In sixteen human cadaver knees a bucket handle tear was created at the posterior horn of the medial and lateral meniscus. The lesion was repaired using two biodegradable implants (either Stingerª, Arrow¨, Dartª or Meniscal Screwª) on each occasion. Loading was compared to intact menisci and menisci after suture repair using 2/0 Ethibond. The specimens were mounted into specially designed jigs, taking all degree of freedom of the knee joint into account, and þxed to a material testing machine (Bionix 858 MTS). Constant loading of 350 N was performed during knee motion of 0¡Ð90¡ of ßexion. The meniscofemoral pressure was measured using the Tekscansystem. All þxation techniques were tested þve times. Results: Increased joint loading at the posterior horn occurred with increased ßexion angle of 0¡, 30¡, 60¡ and 90¡ of knee ßexion in the medial and lateral compartment (p< 0.05). No signiþcant increase in joint loading was noticed after meniscus repair with biodegradable implants. Conclusions: Biodegradable implants do not cause higher meniscofemoral joint loading due to meniscus implants in the posterior horn and resulting cartilage damage at the femoral condyle is unlikely.