There have been mixed reports of the contribution of the anterior cruciate ligament (ACL) to the overall envelope of tibial rotational stability. The effect of single bundle ACL reconstruction on the separate components of internal and external rotational stability respectively is also unclear.

We determined the internal and external rotation, and antero-posterior movement of the knee before and after single bundle computer assisted reconstruction of the anterior cruciate ligament (ACL) in 57 patients. The Orthopilot^® ACL (v2) software (BBraun, Aesculap) was used.

The mean overall range of tibial rotation was also significantly reduced from 30.5 degrees to 16 degrees (p< 0.0001). The mean internal rotation was significantly reduced from 16 degrees to 8 degrees (p< 0.0001). Mean external rotation was also significantly reduced from 15 degrees to 8 degrees (p< 0.0001). Unlike previous studies we did not find a greater reduction of internal rotation compared with external rotation. The mean antero-posterior movement of the tibia was significantly reduced from 12mm to 4mm (p< 0.0001).

The results of this study seem to indicate that computer assisted single bundle ACL reconstruction results in a significant intraoperative improvement in both internal and external rotatory stability as well as a significant improvement in antero-posterior stability.

Uncemented total knee arthroplasty (TKA) implants were designed as an alternative to cemented implants. However, critical studies revealed a unique set of complications. At the same time, cemented prostheses continue to yield excellent results. To address some of the issues with uncemented implants, porous coatings were introduced. This follow-up study reports the early results of Plasmapore^® coating in Navigated uncemented rotating platform TKA.

277 patients who had consecutively undergone a Navigated TKA procedure with the e.motion knee endoprostheses were followed up at the Bluespot Knee Clinic in Blackpool, UK. Of these 277 patients, 91 received an uncemented TKA between May 2005 and September 2007. The prosthesis is coated with a 350μm plasma-sprayed titanium layer. All procedures were carried out by the senior author (SACS). The Orthopilot navigation system was used to accurately restore the axial alignment of the implants.

Men comprised 51% and women 49%. The mean age was 69 years and the mean BMI was 30. There were 50 right and 41 left knees. The mean operating time was 59 minutes. Of the 91 patients who received an uncemented e.motion TKA, 84 patients had at least 1 follow-up assessment. The average follow-up period for these 84 cases was 7 months. The integrated Knee Society Score (KSS) defined as the sum of functional and clinical KSS, was recorded for all 91 patients preoperatively and had a mean of 78. The KSS had increased to 182 after 4 months, 193 after 1 year and 198 after 2 years. Oxford score was recorded for 87 of the 91 patients preoperatively. The average preoperative score was 44. It had decreased to 18 after 4 months, and 16 after 1 year and 13 after 2 years.

Radiological examination showed no evidence of periprosthetic lucency and no subsidence.

There were 5 DVTs with 2 pulmonary embolisms, 2 cases of reflex sympathetic dystrophy, 2 stitch abscesses, 2 haematomas, and 9 cases of wound erythema. These preliminary findings compare favourably with published series of cemented TKAs. They have prompted a more detailed review which is in progress.

Previous studies of osteoarthritic knees have examined the relationship between the variables body mass index (BMI) and weight on the one hand and coronal plane deformity on the other. There is a consensus that weight and BMI are positively correlated to the degree and progression of a varus deformity. However, there does not appear to be a consensus on the effect of these variables on knees with a valgus deformity. Indeed, the view has been expressed that in knees with a severe deformity a relationship might not exist. A review of these studies reveals that in all cases, the alignment of the lower limb was obtained from a standing antero-posterior long leg radiograph. In no cases was the deformity in the sagittal plane measured. This study analyses the relationship between BMI, weight, deformity in the sagittal plane and valgus deformity.

The study group consisted of 73 patients with osteoarthritis and valgus knees. All of them had failed conservative treatment for their symptoms and were listed for navigated TKA. Their weight and height were measured two weeks preoperatively and the BMI calculated. At operation the coronal and sagittal deformities were measured using the Orthopilot^® navigation system (BBraun Aesculap, Tuttlingen). The results were analysed using SPSS 15.

Regression analysis showed a significant relationship (p< 0.05) with a negative correlation between valgus deformity and weight. the correlation coefficient for flexed knees (−0.59) showed a moderately strong relationship whereas that for extended knees (−0.38) showed a relatively weak relationship.

It is acknowledged that there is an increased force on the lateral compartment with increased valgus deformity. a larger deformity causes a larger moment arm about the centre of the knee. this study has shown that at the time of surgery, individuals with lower weights have larger valgus deformities. we postulate, therefore, that when the moment due to the weight of the individual and the length of the moment arm exceeds a certain value, a symptomatic threshold is crossed. in the presence of a fixed flexion deformity, the force on the patella-femoral joint is increased, contributing further to the onset of discomfort.

Further investigation into the subsets of valgus knees appears to be warranted.

Navigated Total Knee Arthroplasty (TKA) is a new technique in our hospital. Any new procedure can be associated with both technical difficulties and difficulties due to patient and theatre staff expectations. The aim of this study was to demonstrate our learning curve and assess patient and staff acceptance. We highlight common technical problems unique to navigation and offer our solutions.

A prospective study of 231 consecutive Emotion TKA were implanted over a 30 month period with Orthopilot version 4.2 Navigation system using soft tissue management (BBraun Aesculap, Tutlingen). They were done by a single knee surgeon previously experienced only in non-navigated TKA. Patient height and weight were measured preoperatively and the BMI calculated. Tourniquet times were recorded digitally with fixed timing criteria. Informed consent was obtained.

Our results showed a significant decrease of tourniquet time with experience (p=< 0.0001) with other possible factors being preoperative deformity and BMI. There was full patient acceptance with the exception of the first patient. The surgical team had to modify patient positioning on the operating table, setup of the theatre and navigation equipment, placement of the scrub staff and delegation of tasks.

Navigated Emotion TKA with Orthopilot software provided a comfortable learning curve. It was readily acceptable to patients and staff and has been adopted as our standard practice. The discussion of problems and the introduction of solutions had a positive effect on building our team. Further investigation is needed to elucidate other variables that affect the tourniquet time.

Valgus knees present a surgically demanding challenge. Dissimilar bone and soft-tissue deformities compared to varus knees complicate restoration of proper alignment, positioning of components, and attainment of joint stability. Our study examined the relationship between tourniquet time and valgus deformity.

A prospective study of all valgus knees were implanted over a 30 month period with Emotion Ortho-pilot version 4.2 Navigation system (BBraun Aesculap, Tutlingen). They were done by a single knee surgeon. Tourniquet times (TT) were recorded digitally with fixed timing criteria. The software recorded all pre- and post-operative deformities. We performed the lateral parapatella approach for all valgus knees. No patella resurfacing was done but all tibiae were cemented.

There were a total of 56 valgus knees (1° to 22°, Mean 5.9°, SD 4.9). The TT varied from 42 min to 121 min (mean 72 min, SD 17.4). There was a statistically significant relationship between TT and Valgus deformity. Tourniquet Time = 59.6 + 2.1 * Pre-operative Valgus (p= < 0.0001, R² = 36.4%)

Thirty six percent of the observations were explained by this analysis. Other factors will need to be considered in future studies. This equation can be used as a guide in the allocation of theatre time. It applies to a specific surgical team and we would expect different teams to have different coefficients. This may be useful in comparisons of different teams.