Paolo Barbadoro

Conventional versus computer-assisted surgery in total knee arthroplasty: comparison at ten years follow-up

PurposeComputer-assisted systems (CAS) for total knee arthroplasty (TKA) were expected to result in more accurate prosthesis implantation, better patient outcomes, and longer implant survival when compared to conventional instrumentation (CI). The aim of this study was to compare two groups of patients operated using CAS or CI at ten years follow-up.MethodsOne hundred twenty TKA patients, 60 using CAS and 60 using CI, were contacted after a decade for follow-up. Eligible patients received radiological examination to assess the lower-limb mechanical axis. They were also clinically assessed using the Knee Injury and Osteoarthritis Outcome Score (KOOS) and the Knee Society Score for Knee (KSS-K) and Function (KSS-F) Scoring. Kaplan-Meier survival analysis was performed to assess revisions, not for post-traumatic reasons.ResultsIn CAS and CI groups, the lower-limb mechanical axis was 1.7° ± 2.4° and 1.5° ± 2.8°, respectively; corresponding KOOS values were 82.3 ± 14.3 and 78.6 ± 14.4; KSS-K values were 85.9 ± 11.1 and 85.0 ± 9.7; KSS-F values were 82.2 ± 19.3 and 83.8 ± 18. For these assessments, the differences between the two groups were not statistically significant (p > 0.05). Two CAS (3.8%) and three CI patients (5.7%) were revised. The Kaplan-Meier analysis showed no significant differences between the two groups.ConclusionsNo significant differences were found at long-term follow-up in terms of radiographical-clinical outcomes and of implant survival between TKA operated using CAS or CI.

Results at a minimum follow-up of 5 years of a ligaments-compatible total ankle replacement design

BACKGROUND A new design of 3-part ankle replacement was developed to achieve compatibility with the natural ligaments by allowing certain fibers to remain isometric during passive motion. METHODS We evaluate 75 ankle prostheses implanted from July 2003 to December 2008, at a mean follow-up 6.5±1.1years (range 5-9 years). The mean age at surgery was 62±13years (range 29-82). RESULTS The mean AOFAS scores achieved at pre-op and at last follow-up were respectively 37±5 (23-45) and 78±8 (64-98). (p<0.001). Clinical range of motion of the ankle measured by goniometer pre op was 1°±2 of dorsiflexion and 12°±4° of plantarflexion; at last follow-up range of motion increased to 6°±5° in dorsiflexion (p<0.01) and 18°±7° in plantarflexion (p<0.05). Radiographs showed no loosening and little signs of radiolucency. Two revisions necessitated component removal, neither for implant loosening. The overall survival rate was 97.3%. CONCLUSIONS Function and Range-of-motion showed significant improvements. These results demonstrate that ligaments-compatible shaped talar and tibial components, with a fully conforming interposed meniscal bearing, can provide satisfactory survival rates and clinical outcomes in the middle term.

Three-dimensional patellar tendon fibre kinematics in navigated TKA with and without patellar resurfacing

PurposePhysiological elongation and orientation of patellar tendon fibres are among the scopes of total knee arthroplasty, but little is known in the three dimensions. The study aims to assess in vitro these variations at the intact and replaced knee, with and without patellar resurfacing. It was hypothesised that fibre patterns differ before and after prosthesis implantation, and between specific prosthesis designs. It was also expected that patellar resurfacing would affect relevant results.Methods Measurements from 16 intact cadaver knees free from anatomical defects are here reported using a surgical navigation system. Data were collected at the intact joint and after implantation with cruciate-retaining or posterior-stabilised prosthesis designs, with and without patellar resurfacing. Relevant anatomical landmarks and patellar tendon attachments were digitised. Anatomical reference frames in the femur, tibia and patella were defined to measure component implantation parameters. Representative tendon fibres were defined as the straight line segments joining the two extremities. Changes in length and orientation of these fibres were calculated and reported versus flexion at the intact knee and after prosthesis implantation, both with and without patellar resurfacing.ResultsA good intra- and inter-specimen repeatability was found at the intact and replaced knees. In both prosthesis designs, the patterns of fibre lengthening were similar to those in the intact knee, though significant differences were observed before and after patellar resurfacing. Corresponding fibre orientations in the frontal and sagittal planes showed significantly smaller ranges than those in the corresponding intact joints. More natural patterns were observed in the knees implanted with the posterior-stabilised design. Significant correlations were identified between patellar component implantation parameters and both patellar tendon fibre elongation and orientation.ConclusionsDifferences, however small, in patellar tendon fibre elongation and orientation were observed after total knee arthroplasty. The posterior-stabilised design provided better results, whereas patellar resurfacing affected significantly normal patellar function. In the clinical practice, the present findings can contribute to the understanding of current prosthesis designs and patellar resurfacing, recommending also enhanced care during this surgery.

Knee Prosthesis Navigation

Total Knee Arthroplasty (TKA) represents an effective technique to treat advanced and debilitating knee arthritis. However at long term follow-up the risk of TKA failure still remains a concern. Nowadays the major causes of failures and patient’s dissatisfaction, in addition to infection, are a prosthesis that remains instable or is not well aligned on sagittal, transverse or coronal plane. All these situations, in fact, could lead to anterior knee pain, arthrofibrosis, wear or loosening. Therefore, was developed the Computer-Assisted Surgery (CAS), a device that helps the surgeon to position the prosthesis component in a much more accurate way than the conventional instrumentation. In fact, via intra-operative anatomy-based tracking of the tibio-femoral joint, CAS allows more precise bone cuts, more accurate prosthesis components implantation, more controlled soft tissue balance and targeted Mechanical Axis restoration. The aim of this chapter is to present and explain which are the main surgical landmarks of CAS, so how it works and how it could help the surgeon being much more precise with bone cuts and control instantly how the resections could influence the final alignment and the stability of the prosthesis.

TKA: Measured Resection Technique

Good clinical outcomes for total knee arthroplasty (TKA) can be obtained if the soft tissues are well balanced and the prosthetic components are properly oriented, combined with joint line restoration. The correct rotational alignment of the femoral component is critical because it determines patellar groove position and flexion gap stability. Improper alignment can also induce anterior knee pain, arthrofibrosis, and torsional stress on the tibial component that could lead to wear or loosening [1–3, 7, 8].

La cinematica femoro-rotulea nell’artroplastica di ginocchio navigata

Despite a large percentage of total knee arthroplasty failures in disorders at the patellofemoral joint, current navigation systems do not track the patella. A new navigated technique has been developed recently, which includes a novel instrumentation. The aim of this study is to report an early experience of intra-operative patellar motion assessment.