The results of total knee arthroplasty are inferior in younger patients. The challenge today is therefore to develop designs and concepts that will last at least 25 years. This thesis has evaluated the fixation to bone of modern designs of knee prostheses uring RSA analysis. Coating implant surfaces with hydroxy-apatite have proven to enhance fixation to bone. Addition of screws for fixation of the tibial component enhances the fixation, but has negative side effects such as osteolysis around the screws, in turn leading to a higher risk of component loosening. The magnitude and pattern of migration was studied in a randomized study of uncemented tibial implants coated with hydroxy-apatite with and without additional screw fixation in patients younger than 65 years. The uncemented implants migrated initially more than the cemented implants that constituted the control group. Both uncemented groups stabilized at 3 monthes with no further migration, while the cemented implants showed a continuous migration up to the 2 year follow-up, indicating continuous bone resorption at the implant-bone interface, a fact that might lead to an increased risk of late implant loosening. This may not be a problem in older patients, but may have consequences for long-term fixation in younger patients. There was no difference between the two uncemented groups indicating that screws do not improve fixation. Hydroxy-apatite coated knee implants might be well suited for younger patients. Mobile bearing total knee arthroplasty theoretically uncouples the forces at the implant-bone interface, thus improving fixation of the implant to bone. The magnitude and pattern of migration of a cemented mobile bearing knee arthroplasty and a fixed bearing total knee arthroplasty was compared in a randomized study. The results showed that mobile bearings did not improve fixation. Trabecular metal, a new material recently introduced for total knee arthroplasty, has several theoretical advantages. Trabecular metal tibial implants were evaluated in a randomized study in patients younger than 60 years. The implants displayed the typical migration pattern for uncemented implants with greater migration initially followed by early stabilization. The majority of the trabecular metal implants subsided into the bone with no lift-off. Lift-off has the potential of exposing the interface to joint fluid with the potential risk of bone resorption and late loosening, and is commonly seen in metal-backed implants. The finding of absence of lift-off is regarded beneficial for uncemented fixation. Trabecular metal tibial implants might be suited for younger patients. The optimal mode of fixation of the femoral component is yet to be established. Comparing cemented femoral components with uncemented femoral components in a randomized study in patients younger than 60 years revealed no differences of the magnitude or the pattern of migration. Uncemented femoral component seems equally as good as cemented components in younger patients.

Traditionally, orthopaedic surgical training has primarily taken place in the operating room. Given the growing trend of decreasing resident work hours in North America and globally due to political mandate, training time in the operating room has generally been decreased. This has led to less operative exposure, teaching, and feedback for orthopaedic surgery residents. To solve this problem, a 3D serious game that was designed for the purpose of training orthopaedic surgery residents the steps comprising the total knee replacement procedure. Real-time, 3D graphical and sound rendering technologies are employed to provide sensory realism ensuring that the knowledge gained within the serious game can be more easily recalled and applied a real world scenario. A usability study to address user perceptions of the game’s ease of use, and the potential for learning and engagement was conducted. Results indicate that the serious game is easy to use, intuitive, and stimulating. / UOIT

Source: Masters Abstracts International, Volume: 47-06, page: 3565. Adviser: Benjamin Amick. Includes bibliographical references.

published_or_final_version / Orthopaedic Surgery / Master / Master of Philosophy

The purpose of this study was to determine the effectiveness of a modified sitting position straight leg raise on vastus medialis oblique (VMO) strength and EMG activity as compared to a traditional straight leg raise. A total of twenty-three subjects were recruited for this study. The subjects were randomly assigned to one of the following groups: (group I) modified straight leg raise (MSLR), and (group II) straight leg raise (SLR). The exercise program was three weeks long. University procedures for the protection of human subjects were followed. The subjects began with a 5 minute warm-up on a Cybex stationary bike set at 90 revolutions / minute. The subject then had electrodes placed on the Vastus Lateralis (VL) and Vastus Medialis Oblique (VMO). A Macintosh computer was used to record the EMG data. The subject then performed a standard Cybex test for knee flexion and extension. The Cybex dynamometer was placed at the knee joint line, the chair back tilt was at 85 degrees, the hip, chest, and thigh restraints were all fastened. The subjects in group I (Modified sitting SLR) and II (SLR) then returned the next day for their first rehabilitation lesson. Each subject group then participated in their respected exercise program for a total of three weeks. After three weeks of rehabilitation, the subjects retested using the same procedures followed in the pretest. A two tailed t-test was used to determine significance of the difference between means of the two groups. No significant differences were found between the two groups. / School of Physical Education

Background: Cryotherapy is commonly used during physiotherapeutic rehabilitation of patients following total knee replacement (TKR). Evidence for treatment effectiveness within the current literature is contradictory and there are no clinical guidelines to inform cryotherapy treatment within this particular patient group. This study surveys current cryotherapy treatment efficacy in the acute post-operative management of TKR patients. Methods: In total 263 senior physiotherapists completed and returned a postal questionnaire, which, using open and closed questions investigated the use of cryotherapy following TKR. Survey results were used to inform a pragmatic randomized clinical trial (RCT) involving 133 consecutive TKR patients. The RCT investigated cryotherapy treatment efficacy in the acute post-operative management of TKR patients. Patients were randomized into three groups; no cryotherapy (NC), delayed cryotherapy (DC) and immediate cryotherapy (IC). The primary outcome measure was post-operative pain with knee swelling, active range of motion (AROM), function and levels of physiotherapy input assessed as secondary outcome measures. Observations were taken pre-operatively and at 3, 7 and 42 days post-operatively. Results: The survey reported that 33% of respondents used some form of cryotherapy routinely following TKR surgery. The two main methods of cryotherapy application were Cryocuff (59%) and crushed ice (30%). Treatments were most frequently applied between 24 hrs and 48 hrs post-surgery for 20 minutes, twice a day. Chi square analysis indicated significant differences (p<0.01) in between NHS and private sites relating to a lack of cryotherapy resources and treatment time for cryotherapy in the NHS. A lack of proven efficacy was the most cited reason for not applying cryotherapy treatment, and swelling the most common treatment indicator. There was particular uncertainty regarding the cleaning and sterilization of the Cryocuff device. The RCT indicated that patients in IC group had significantly less post-operative pain than the NC and DC groups at 3 days. Mean difference (p <0.05, 95% CI) in post-operative analogue scores (VAS, scale 0-10) was -1.6 (p <0.01, CI -2.49- to -0.707) for IC and NC; and -0.922 (p= 0.044, CI -0.183 to -0.009) for IC and DC groups. At 7 and 42 days there were significant reductions in VAS scores for both cryotherapy groups compared to the NC group. There was significant improvement in knee swelling, AROM, ability to transfer and need for additional physiotherapy in both cryotherapy treatment groups although no significant reduction in opiate requirement was found. Conclusions: In current clinical practice there was little consensus regarding treatment indicators, method of application and management of cryotherapy following TKR. However, in a RCT the use of cryotherapy combined with compression, as compared to a no cryotherapy control, led to significant reductions in patient reported pain, less post-operative swelling, greater recovery of AROM, faster return of function and less reliance on OPD physiotherapy treatment. It is concluded that cryotherapy combined with compression has an important role to play in the acute rehabilitation of TKR and should be considered as part of routine management.

[Truncated abstract] Unicondylar knee arthroplasty (UKA) has re-emerged as a successful treatment option for isolated single compartment tibio-femoral joint osteoarthritis. However despite its increasing use, controversy still remains over fixed or mobile bearing tibial components, as there is a lack to prospective randomised studies reported in the literature. In addition, the theoretical advantages of the mobile bearing for knee kinematics, kinetics and clinical outcome have not been evaluated in vivo. The aim of this research study was to explore the clinical and biomechanical outcomes of the fixed and mobile bearing UKA. . . . When the results for the both studies were combined, utilising the Preservation and MG fixed bearing prostheses, there was a significant relationship between knee adduction moment, and a poor prognosis predicted from RSA. Those patients with translation or rotation of the tibial component in any direction above 1mm and 1.5 degrees respectively were considered to have a poor prognosis for long term fixation. Of the 28 patients, the 8 patients considered to have a poor prognosis, had increased knee adduction moments post-surgery (mean difference = 1.66Nm.kg-1, p = 0.007). There was no difference between the groups for knee flexion moment (mean difference 0.16Nm.kg-1, p = 0.844). Pre-surgery gait was unable to predict the post-surgery outcome, due to the significant changes in gait from pre- to post-surgery. Care must taken when implanting the Preservation mobile bearing prosthesis, as long term outcome is questionable. The mobile bearing prosthesis also produced the worst clinical outcome, however the theoretical advantages of the mobile bearing does not affect gait. Gait analysis is a useful tool to identify patient who are overloading their prosthesis, leading to potential early failure. Identification of these gait patterns can allow for early intervention to reduce joint load, and possible extend the longevity of the prosthesis.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 5 uppsatser. - På omsl. felaktigt: Karolinska University Press.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2006. / Härtill 4 uppsatser.