Comparison between patient-specific instruments and conventional instruments and computer navigation in total knee arthroplasty: a randomized controlled trial

Current state of the art in total knee arthroplasty computer navigation

PURPOSE

Computer-assisted surgery in orthopaedics is passing through the initial adapter phase of technology adoption. It started more than 20 years ago, but the uptake of technology is still not widespread. The purpose of this article is to introduce the reader to the basic technology and familiarize with the terminology used in the computer navigation.

METHODS

During this time, the technology has matured and we have the evidence to prove its benefits for patients. Not only does it help placing the prosthetic components in correct orientation, it also helps with other parameters like blood loss and fat embolism reduction. In addition to being a teaching and training tool, it has also opened new areas of research which now question the traditional practices. Since it is not in commonly used, the basic aspects of computer navigation are not very well known.

RESULTS

This paper outlines some important definitions and restates the classification of navigation within the spectrum of computer-assisted technologies; it then elaborates on the key principles behind navigation in knee arthroplasty and goes through some of the differences between navigation systems. Finally, it describes in some detail the surgical steps with an image-free knee navigation system.

CONCLUSIONS

Computer-assisted navigation is not mainstream yet, but this article should help readers unfamiliar with the technology to understand the basic terms and how it actually works.

LEVEL OF EVIDENCE

III.

Does Patient-Specific Instrumentations Improve Short-Term Functional Outcomes After Total Knee Arthroplasty? A Systematic Review and Meta-Analysis

BACKGROUND

Patient-specific instrumentation (PSI) has been recently introduced in knee arthroplasty. There is no strong evidence from meta-analysis on comparison of functional outcomes between PSI and conventional instrumentation.

METHODS

Literature search of electronic databases PubMed, MEDLINE, and Cochrane Library for published randomized controlled trials was undertaken. Search was done using a predesigned search strategy. Eligible studies were critically appraised for the methodological quality using Cochrane Collaboration's tool. Functional scores used for meta-analysis were Knee Society Knee Score, Knee Society Function Scores, Oxford Knee Score, Western Ontario and McMaster Universities Arthritis Index, and Visual Analogue Scale score for pain (0-10 scale).

RESULTS

Five randomized controlled trials involving 379 total knee arthroplasties were eligible to be included in the meta-analysis. No significant improvement in short-term functional outcomes was seen after using PSI compared to the control group in terms of Knee Society Knee Score (weighted mean difference 0.65, 95% CI -4.41 to 5.70, P = .80) and Knee Society Function scores (weighted mean difference 0.01, 95% CI -3.26 to 3.28, P = .99), Oxford Knee Score (weighted mean difference 3.36, 95% CI -3.48 to 10.00, P = .34), Western Ontario and McMaster Universities Arthritis Index (weighted mean difference -7.47, 95% CI -23.94 to 8.99, P = .37), and Visual Analogue Scale score for pain (weighted mean difference -0.10, 95% CI -0.41 to 0.21, P = .53).

CONSLUSION

Current literature is insufficient to address whether there is a benefit of PSI in total knee arthroplasty in terms of improvement in functional outcomes.

Patient-specific instrumentation does not improve radiographic alignment or clinical outcomes after total knee arthroplasty

Background and purpose - Patient-specific instrumentation (PSI) for total knee arthroplasty (TKA) has been introduced to improve alignment and reduce outliers, increase efficiency, and reduce operation time. In order to improve our understanding of the outcomes of patient-specific instrumentation, we conducted a meta-analysis. Patients and methods - We identified randomized and quasi-randomized controlled trials (RCTs) comparing patient-specific and conventional instrumentation in TKA. Weighted mean differences and risk ratios were determined for radiographic accuracy, operation time, hospital stay, blood loss, number of surgical trays required, and patient-reported outcome measures. Results - 21 RCTs involving 1,587 TKAs were included. Patient-specific instrumentation resulted in slightly more accurate hip-knee-ankle axis (0.3°), coronal femoral alignment (0.3°, femoral flexion (0.9°), tibial slope (0.7°), and femoral component rotation (0.5°). The risk ratio of a coronal plane outlier (> 3° deviation of chosen target) for the tibial component was statistically significantly increased in the PSI group (RR =1.64). No significance was found for other radiographic measures. Operation time, blood loss, and transfusion rate were similar. Hospital stay was significantly shortened, by approximately 8 h, and the number of surgical trays used decreased by 4 in the PSI group. Knee Society scores and Oxford knee scores were similar. Interpretation - Patient-specific instrumentation does not result in clinically meaningful improvement in alignment, fewer outliers, or better early patient-reported outcome measures. Efficiency is improved by reducing the number of trays used, but PSI does not reduce operation time.

No difference in clinical outcome between patient-matched positioning guides and conventional instrumented total knee arthroplasty two years post-operatively

Aims

We wished to compare the clinical outcome, as assessed by questionnaires and the rate of complications, in total knee arthroplasty (TKA) undertaken with patient-matched positioning guides (PMPGs) or conventional instruments.

Patients and Methods

A total of 180 patients (74 men, 106 women; mean age 67 years) were included in a multicentre, adequately powered, double-blind, randomised controlled trial. The mean follow-up was 44 months (24 to 57).

Results

There were no significant or clinically relevant differences between the two groups for all outcome measures (Knee Society Score, p = 0.807; Oxford Knee Score, p = 0.304; Western Ontario and McMaster osteoarthritis index, p = 0.753; visual analogue scale for pain, p = 0.227; EuroQol-5D-3L index score, p = 0.610; EuroQol-5D-3L VAS health, p = 0.968.) There was no difference in the rate of complications (p = 0.291).

Conclusion

PMPGs are already in relatively common use and their short-term clinical results are equal to conventional instrumented TKA. Cite this article: Bone Joint J 2016;98-B:939–44.

Fixing a fractured arthrodesed hip with rapid prototype templating and minimal invasive plate osteosynthesis

CASE

We present an elderly lady with an intertrochanteric fracture of a previously fused hip. A 3D printed model of her pelvis and femur was used for implant templating before surgery. Minimal invasive fixation was performed with a spanning reversed distal femur locking plate without the need for removal of the previous implant. Multiple long locking screws were placed in the supra-acetabular region. The patient had union in 4 months, return to function and no complication.

Conclusion

The technique allowed us to optimize implant selection and insert screws safely at difficult trajectories using minimal invasive surgery.