Pressure ulcers are a common occurrence in individuals with spinal cord injuries, and are attributed to prolonged sitting and limited mobility. This therefore creates the need to better understand soft tissue composition, in the attempt to prevent and treat pressure ulcers. In this study, novel approaches to imaging the soft tissue of the buttocks were investigated in the loaded and unloaded position using ultrasound (US) and magnetic resonance imaging (MRI).

Twenty-six able-bodied participants (n=26, 13 males and 13 females) were recruited for this study and 1 male with a spinal cord injury. Two visits using US were required, as well as one MRI visit to evaluate soft tissue thickness and composition. US Imaging for the loaded conditions was performed using an innovative chair which allowed image acquisition in the seated upright position and MRI was done in the lateral decubitus position and loading was applied to the buttocks using a newly developed MRI compatible loader. The unloaded condition was a lateral decubitus position. Soft tissue was measured between the peak of the ischial tuberosity (IT) and the proximal femur and skin.

Tissue thickness reliability for US was excellent, ICC=0.934–0.981 with no significant differences between the scan days. US and MRI measures of tissue thickness were significantly correlated (r=0.68–0.91). US underestimated unloaded tissue thicknesses with a mean bias of 0.39 – 0.56 for total tissue and muscle + tendon thickness. When the buttocks were loaded, total tissue thickness was reduced by 64.2±9.1%.

US assessment of soft tissue thicknesses was reliable in both positions. The unloaded measurements using US were validated with MRI with acceptable limits of agreement, albeit tended to underestimate tissue thickness. Tissue thickness, but not fatty infiltration of muscle played a role in how the soft tissue of the buttocks responded to loading.

Purpose: Previous research has reported that increasing the posterior tibial slope through an opening wedge osteotomy results in an anterior shift in the position of the tibia relative to the femur. However, the effect of this on anterior cruciate ligament (ACL) strain remains insufficiently understood. The purpose of this study was to examine the relationship between tibial slope and tibial translation, as well as between tibial slope and ACL strain. It was hypothesized that increasing the posterior tibial slope would result in an increase in anterior tibial translation thereby increasing strain in the ACL.

Methods: Five cadaveric knees were subjected to a randomized experimental design study. One knee was excluded due to failure of a strain gauge during experimentation, resulting in data for four knees. The femoral and tibial portions of the knee were potted with PMMA and fixed using fixation pins. An anterior-based osteotomy was performed with no osteotomy plate present. A strain gauge was then placed in the anteromedial bundle of the ACL. Each knee was mounted at a flexion angle of 15° and loaded with various combinations of A-P loads (18N, 108N, 209N) and axial loads (216N, 418N), according to the study design. Osteotomies of 5mm and 10mm were then performed and measurements of strain and tibial translation were taken after each according to the study design. Tibial slopes were determined through lateral fluoroscopic imaging.

Results: As posterior tibial slope increased, anterior tibial translation increased as anticipated. However, contrary to expectations, as posterior slope increased, ACL strain decreased. One explanation for this result could be that by performing the osteotomy, the insertions sites of the ACL were being moved closer together resulting in increased ACL laxity. At higher slope angles, translation levels off, suggesting constraint of some tissue besides the ACL.

Conclusions: Although increasing the tibial slope through opening wedge osteotomy leads to an anterior tibial translation, there is no increase in strain on the ACL. Further studies are needed to examine the effect of opening wedge osteotomy on other soft tissue restraints of the knee.

Aim: To compare the function in two groups of high demand patients with a total knee arthroplasty (TKA) – one group using a posterior cruciate sacrificing (PCS) prosthesis and the other a posterior cruciate retaining (PCR) prosthesis of similar design.

Method: Patients were eligible for the study if they were greater than two years from surgery, less than 65 years of age and without other co-existing morbidity to significantly decrease their physical activities. Group A underwent surgery by one surgeon who routinely retained the posterior cruciate ligament whereas Group B underwent surgery by one surgeon who routinely sacrificed the PCL. A mobile bearing TKA of similar design was used in each group. All patients were selected and assessed by an independent assessor using a questionnaire developed specifically to assess higher levels of activity not usually assessed by other knee scores.

Results: Group A (28 TKA in 20 patients) were matched with Group B (25 TKA in 19 patients) for age, length of follow-up and range of motion. The gross activity score was 3.36 in Group A compared with 3.12 in Group B. The combined walking, running and stair climbing score was significantly better in Group A (7.68 compared to 6.64 in Group B). Group B perceived their TKA was closer to a normal knee (2.00 compared to 2.32) with decreased anterior knee pain.

Conclusions: Retaining the PCL in TKA results in better function without significant complications.

We compared function in two groups of high demand patients who had undergone total knee arthroplasty (TKA), one group using a posterior cruciate sacrificing (PCS) prosthesis and the other a posterior cruciate retaining (PCR) prosthesis of similar design.

Patients were eligible for the study if surgery had been performed more than two years ago and they were under 65 years of age and had no coexisting morbidity that markedly decreased their physical activities. One surgeon operated on 28 patients in group A (20 TKAs), routinely retaining the posterior cruciate ligament (PCL). A second surgery operated on 19 patients in group B (25 TKAs) and routinely sacrificed the PCL. A mobile bearing prosthesis of similar design was used in each group. Patients were independently selected and assessed using a questionnaire specifically developed to assess higher levels of activity not usually assessed by other knee scores. Patients in the two groups were matched in terms of age, range of motion and follow-up

The gross activity score was 3.36 in group A and 3.12 in group B. The combined walking, running and stair-climbing score was in group A (7.68) than in group B (6.64). Patients in group B had decreased anterior knee pain and perceived their TKA closer to a normal knee (2.00 compared to 2.32).

We conclude that retaining the PCL in TKA results in better patient function without obvious complications.