Total knee arthroplasties from the origin to navigation: history, rationale, indications.

Since the early 1970s, total knee arthroplasties have undergone many changes in both their design and their surgical instrumentation. It soon became apparent that to improve prosthesis durability, it was essential to have instruments which allowed them to be fitted reliably and consistently. Despite increasingly sophisticated surgical techniques, preoperative objectives were only met in 75% of cases, which led to the development, in the early 1990s, in Grenoble (France), of computer-assisted orthopaedic surgery for knee prosthesis implantation. In the early 2000s, many navigation systems emerged, some including pre-operative imagery ("CT-based"), others using intra-operative imagery ("fluoroscopy-based"), and yet others with no imagery at all ("imageless"), which soon became the navigation "gold standard". They use an optoelectronic tracker, markers which are fixed solidly to the bones and instruments, and a navigation workstation (computer), with a control system (e.g. pedal). Despite numerous studies demonstrating the benefit of computer navigation in meeting preoperative objectives, such systems have not yet achieved the success they warrant, for various reasons we will be covering in this article. If the latest navigation systems prove to be as effective as the older systems, they should give this type of technology a well-deserved boost.

Results with eight and a half years average follow-up on two hundred and eight e-Motion FP® knee prostheses, fitted using computer navigation for knee osteoarthritis in patients with over ten degrees genu varum.

PURPOSE: The aim of this study was to analyse the clinical and radiographic results of 208 e-Motion® posterior cruciate-retaining, mobile bearing prostheses (BBraun-Aesculap, Tuttlingen, Germany) fitted using computer navigation, for knee osteoarthritis with a genu varum greater than 10°. METHODS: One hundred ninety-two patients were operated on with 208 e-Motion® prostheses fitted, between January 2006 and December 2011, using the OrthoPilot® computer navigation system. Average pre-operative IKS score was 70 ± 27 points (6-143) with a function score of 38 ± 20.5 (0-90) and a knee score of 32.5 ± 13 (0-63). Average flexion was 116.5° ± 13° (65-140°). Average pre-operative HKA angle was 166° ± 3° (154-169°). RESULTS: 2Results are available for 134 patients, with a total of 150 knees operated on (38 lost to follow-up and 20 deceased). Average follow-up was 104.5 months (60-116 months). On last follow-up, the average IKS was 180 ± 22 points (95-200) with 86.5 ± 16 points (25-100) for the function score and 93.5 ± 8 points (55-100) for the knee score. Knee flexion was 116° ± 10.5° (80-135°) and average HKA angle was 179° ± 2° (175-184°). The pre-operative objective was achieved in 90.5% of knees. CONCLUSION: The e-Motion® mobile bearing posterior cruciate-retaining prosthesis, fitted using computer navigation, offers excellent results after an average of 8.5 years follow-up. These results are at least equivalent, even superior, to those of the posterior-stabilised prostheses usually used for this type of deformity.

Computerised navigation of unicondylar knee prostheses: from primary implantation to revision to total knee arthroplasty.

AIM: Computerized navigation of unicondylar knee arthroplasties (UKA) is not a widespread technique. The lifespan of a UKA depends on the quality of its implantation. We know that overcorrection leads to a rapid extension of the osteoarthritis to the opposite side of the knee and undercorrection to a rapid loosening or wear of the prosthesis. Because of these difficulties and following a long experience with navigation of total knee arthroplasties (TKA) and osteotomies around the knee, we began using navigation for revisions to TKA in 2003 and for UKAs in 2008. The aim of this work is to present, firstly, the axial alignment of 79 medial and 19 lateral computer-assisted UKAs and, secondly, the axial alignment of 23 computer-assisted UKA revisions to TKA. METHODS: In all the cases we used the Orthopilot® device (BBraun-Aesculap, Tuttlingen, Germany), which is a non image-based navigation system. RESULTS: For medial prostheses, the main objective was to obtain a post-operative HKA angle of 177° ± 2°, i.e. an under correction of 1-5°. This objective was met in 88.5 % of the cases. For lateral prostheses, the main objective was to achieve a post-operative HKA angle of 183° ± 2°, i.e. also an under correction of 1-5°. This objective was met in 84 % of the cases (3 cases at 186° and no cases of over correction). Regarding UKA revisions, the main objective was to ensure an HKA angle of 180° ± 3°. This was met in 92.4 % of the cases. CONCLUSION: As for TKA and osteotomies, computerized navigation of UKAs and UKA revisions allows the pre-operative goal to be met easily.

Non-operative treatment of four-part fractures of the proximal end of the humerus: results of a prospective and retrospective multicentric study.

PURPOSE: The aim of this study was to evaluate the short- and medium-term results of non-operative treatment of four-part fractures of the proximal end of the humerus. The initial hypothesis was that non-operative treatment of fractures with little or no displacement is equivalent or superior to surgical treatment, and that non-operative treatment is probably insufficient for displaced fractures. METHODS: This was a multicentric, prospective and retrospective study, based on 384 four-part proximal humerus fractures, 58 of which involved non-operative treatments - 37 in the prospective study (Pro-CT4) and 21 in the retrospective study (Retro-CT4). The average patient age was 64 +/- 14 years (39-90); 66 % were female and 34 % male. In 88 % of these cases, non-operative treatment was chosen for the fracture, as there was little or no displacement. In 10 % of cases, non-operative treatment was chosen "by default", due to the patient's medical conditions, as surgery was contraindicated, and in 2 % of cases due to the patient refusing surgery. All patients were reviewed clinically and radiologically, with SSV evaluation, absolute and weighted Constant scores and the Quick DASH score all assessed. The main evaluation criterion was the weighted Constant score which was considered a failure when below 70 %. RESULTS: In the Pro-CT4 study, the average follow-up period was 11 +/- four months (5-18) with functional scores as follows: average SSV: 72 +/- 26 % (8-100); average Constant score: 65 +/- 21 points (21-95); average weighted Constant score: 86 +/- 26 % (32-130); average Quick DASH: 23 +/- 21 (0-64). 27 % of patients had a weighted Constant score below 70 %. In the Retro-CT4 study, the average follow-up period was 38 +/- 13 months (18-62) with functional scores as follows: average SSV: 73 +/- 17 % (30-100); average Constant score: 68 +/- 18 points (33-95); average weighted Constant score: 88 +/- 27 % (47-133); average Quick DASH: 18 +/- 16 (0-48); 24 % of patients had a weighted Constant score below 70 %. CONCLUSION: This study confirms our initial hypothesis. When non-operative treatment of four-part proximal humerus fractures is carried out by choice, the results are excellent. However, when this treatment is carried out "by default" - especially because surgery is contraindicated - the results are disappointing. LEVEL OF EVIDENCE IV: prospective and retrospective studies.