Advantages of patient-specific cutting guides with disposable instrumentation in total knee arthroplasty: a case control study.

BACKGROUND: Total knee arthroplasty (TKA) is most frequently planned using conventional two-dimensional weight-bearing lower limb radiographs and is performed with conventional femoral and tibial cutting guides. Questions have been raised about the accuracy of conventional TKA instrumentation and planning for an anatomically standard or complex joint. Use of computed tomography (CT)-based three-dimensional (3D) templating and patient-specific cutting guides printed in 3D has shown improved postoperative lower limb alignment parameters. This case-control study compared costs and operative times of using CT-based, patient-specific, single-use instruments versus conventional metal instruments for TKA. METHODS: In this case-control, retrospective chart review, all TKAs were performed by one senior surgeon, using the F.I.R.S.T. posterior-stabilised knee prosthesis (Symbios, CH), with a similar protocol and identical operating room setup. Group A included 51 TKAs performed with patient-specific cutting guides and conventional metal instruments. Group B included 49 TKAs performed with patient-specific cutting guides and patient-specific, single-use instrumentation. Operation duration, number of instrumentation trays and sterilisation costs were evaluated. RESULTS: The groups were similar for age, body mass index, hip-knee-ankle angle and operation duration. The mean number of instrumentation trays was 8.0 ± 0.8 for group A (controls) and 5.1 ± 0.9 for group B (p<0.001). The mean sterilisation costs were 380 ± 47 Swiss Francs (CHF) for group A and 243 ± 55 CHF for group B (p<0.001), for a mean cost reduction of 130.50 CHF per intervention in group B. The time interval between two consecutive surgeries was 24 min for group A and 18 min for group B. There were no adverse events or complications, instrument-related or otherwise. CONCLUSION: Compared to conventional instrumentation, use of patient-specific, single-use instruments for TKA reduced the number of instrumentation trays by more than one-third and saved 36% in sterilisation costs. If fabrication costs of single-use instruments are included by the company, the total cost is significantly diminished. There was no operative time advantage for single-use instrumentation.

Are the Cumulated Ambulation Score and Risk Assessment and Prediction Tool useful for predicting discharge destination and length of stay following total knee arthroplasty?

BACKGROUND: Postoperative management of patients undergoing total knee arthroplasty (TKA) is continually changing. Costs related to TKA are driven by implant cost, operating room cost, hospital length of stay (LOS), and rehabilitation approach. Discharges to rehabilitation centers have declined significantly in recent years. AIM: We evaluated the usefulness of the Cumulated Ambulation Score (CAS) and Risk Assessment and Prediction Tool (RAPT) to predict discharge destination and estimate hospital LOS of patients undergoing TKA. DESIGN: Prospective cohort study. SETTING: University hospital inpatients. POPULATION: Patients undergoing elective primary TKA. METHODS: Consecutive patients were prospectively evaluated. Outcome measures were discharge destination and LOS dichotomized at the median (LOS<8 versus LOS≥8). Patients completed five outcome questionnaires and knee range of motion was measured preoperatively. RAPT was considered continuous, and also dichotomized (RAPT≤9 versus RAPT>9; RAPT9). CAS was dichotomized (CAS<11 versus CAS≥11; CAS11). Surgical technique and aftercare were similar for all patients. RESULTS: Sixty-four patients (37 females), mean age 69.3±10.2 years were evaluated. CAS11 and discharge destination were strongly associated: 75.9% of patients with CAS≥11 were discharged home; 85.7% of patients with CAS<11 were discharged to a rehabilitation center (P<0.001). 80.7% of patients with RAPT≤9 were discharged to a rehabilitation center, versus 36.4% of patients with RAPT>9 (P=0.002). Odds ratios for discharge home were 18.9 (CAS11) and 7.3 (RAPT). CAS11 and RAPT were not related to LOS. CONCLUSIONS: The CAS and RAPT can assist clinicians in estimating the discharge destination and developing patient care plans following TKA. However, predicting LOS with such tools alone was inaccurate. CLINICAL REHABILITATION IMPACT: Use of the CAS and RAPT can inform discharge destination and patient care plans following TKA and has the potential to optimise resources and costs. However, due to social and organizational constraints on discharge, predicting LOS with such tools alone revealed to be inaccurate.

Soft tissue artifact assessment during treadmill walking in subjects with total knee arthroplasty.

Accurate measurement of knee kinematics during functional activities suffers mainly from soft tissue artifact (STA): the combination of local surface deformations and rigid movement of markers relative to the underlying bone (also called rigid STA movement: RSTAM). This study proposes to assess RSTAM on the thigh, shank, and knee joint and to observe possible features between subjects. Nineteen subjects with knee arthroplasty were asked to walk on a treadmill while a biplane fluoroscopic system (X-rays) and a stereophotogrammetric system (skin markers) recorded their knee movement. The RSTAM was defined as the rigid movement of the cluster of skin markers relative to the prosthesis. The results showed that RSTAM amplitude represents approximately 80-100% of the STA. The vertical axis of the anatomical frame of the femur was influenced the most by RSTAM. Combined with tibial error, internal/external rotation angle and distraction-compression were the knee kinematics parameters most affected by RSTAM during the gait cycle, with average rms values of 3.8° and 11.1 mm. This study highlighted higher RSTAM during the swing phase particularly in the thigh segment and suggests new features for RSTAM such as the particular shape of some RSTAM waveforms and the absence of RSTAM in certain kinematics during the gait phases. The comparison of coefficient of multiple correlations showed some similarities of RSTAM between subjects, while some correlations were found with gait speed and BMI. These new insights could potentially allow the development of new methods of compensation to avoid STA.

A study compared nine patient-specific indices for musculoskeletal disorders.

BACKGROUND AND OBJECTIVE: Patient-specific quality of life indices show great potential, but certain conceptual and methodological concerns have yet to be fully addressed. The present study reviewed nine patient-specific instruments used in musculoskeletal disorders: the Canadian Occupational Performance Measure (COPM), Juvenile Arthritis Quality of life Questionnaire (JAQQ), McMaster-Toronto Arthritis questionnaire (MACTAR), Measure Yourself Medical Outcome Profile (MYMOP), Patient-Specific Index (PASI) for total hip arthroplasty, Problem Elicitation Technique (PET), Patient Generated Index (PGI) of quality of life, Patient-Specific Functional Scale (PSFS), and Schedule for the Evaluation of Individual Quality of Life (SEIQoL). STUDY DESIGN AND SETTING: Each tool was evaluated for purpose, content validity, face validity, feasibility, psychometric properties, and responsiveness. RESULTS: This critical appraisal revealed important differences in terms of the concept underlying these indices, the domains covered, the item-generation techniques and the scoring (response scale, methods) in each scale. The nine indices would generate different responses and likely scores for the same patient, despite the fact that they all include patient-generated items. CONCLUSION: Although the value of these indices in treatment planning and monitoring at an individual level is strong, more studies are needed to improve our understanding of how to interpret the numeric scores of patient-specific indices at both an individual and a group level.