Is there any range-of-motion advantage to using bearings larger than 36mm in primary hip arthroplasty: A case-control study comparing 36-mm and large-diameter heads.

BACKGROUND: Large-diameter (>36mm) total hip arthroplasty (THA) has developed rapidly since the advent of ceramic-on-ceramic (CoC) bearings and highly cross-linked polyethylene. Theoretically, the increase in diameter reduces the risk of instability, although the advantage of calibers beyond 36mm has not been demonstrated in terms of range-of-motion recovery. We conducted a comparative study with a single prosthesis model to determine whether increasing the caliber beyond 36mm provides: (1) better recovery of range-of-motion, (2) a higher functional score, and (3) reduction of the dislocation rate. HYPOTHESIS: Increasing the range-of-motion by increasing the caliber beyond 36mm provides better range-of-motion. MATERIAL AND METHODS: We analyzed two consecutive, single-operator cementless THA series performed via the mini posterior approach, which differed only in the bearing system (51 metal-on-metal [MoM] with a mean caliber of 45mm±3.3 [range, 40-54] and 61 CoC with a 36-mm caliber). Both series were comparable preoperatively in terms of age, diagnosis, functional scores, preoperative range-of-motion, body mass index, UCLA activity level, and Charnley score. We compared the joint range of movement at follow-up and the gains in range of movement, onset of dislocation, and functional scores (Oxford, Postel-Merle d'Aubigné [PMA]). RESULTS: The mean overall joint range-of-motion was 254°±39° (range, 150-310°) for an 81°±44° (range, -50 to 180°) gain in the MoM group and 256°±23° (range, 200-280°) for an 84°±40° (range, 0-160°) gain in the CoC group (NS). The MoM group presented the following results: Oxford=13.71±3.66 (range, 12-33) for a gain of 24.82 points±7.9 (range, -1 to 40), PMA=17.75±1.06 (range, 11-18) for a gain of 7.78 points±4.01 (range, 2-15). The CoC group had: Oxford=14.98±4.42 (range, 12-36) for a gain of 24.75 points±6.55 (range, 12-40), PMA 17.66±0.7 (range, 14-18) for a gain of 8 points±3.77 (range, 1-15). None of the gains and scores at follow-up differed significantly between the two groups. No episode of dislocation was identified. DISCUSSION: The current trend of increasing femoral head diameters beyond 36mm to improve the gains in joint range-of-motion and function is not warranted. The potential side effects of increasing the caliber call for even greater caution in the use of large-diameter heads because our hypothesis has not been confirmed. LEVEL OF EVIDENCE: Case-control study, level III.

Does primary total knee arthroplasty for acute knee joint fracture maintain autonomy in the elderly? A retrospective study of 21 cases.

INTRODUCTION: Due to poor results and failure encountered in osteosynthesis of peri-articular fracture of the knee, arthroplasty may be suggested to osteopenic elderly subjects. All osteosynthesis techniques entail loss of independence and are associated with elevated mortality. No studies definitively establish better management of such fractures. HYPOTHESIS: Total arthroplasty provides better autonomy after peri-articular fracture of the knee. MATERIAL AND METHOD: Seventy-nine patients aged over 65years were operated on for peri-articular fracture of the knee between April 2008 and March 2013. In 21 cases, treated by a single surgeon, total knee arthroplasty was performed in view of osteopenia or osteoarthritis. Mean age was 79years (range, 68-96years). There were 10 distal femoral and 11 proximal tibial fractures. Mean follow-up was 31months (range, 9-68months). Cases of pathologic fracture, failed osteosynthesis and non-operative management were excluded. All patients showed severe osteopenia on radiology and half already had advanced osteoarthritis. RESULTS: One-year mortality was 14%. At last follow-up, the revision rate was 9.5%. Fifteen patients were followed up. Mean Parker score fell from 7.2 (range, 2-9) preoperatively to 4.6 (range, 0-9) at last follow-up, indicating loss of independence. At follow-up, mean IKS score was 116.6 (range, 0-192) with mean IKS knee score of 78.4 (range, 0-100) and IKS function score of 38.2 (range, 0-100). Mean Oxford score was 36/60 (range, 18-53). Global IKS and IKS function scores were significantly better in case of ASA-2 than ASA-3 (P<0.05). There was no difference between femoral and tibial fractures in terms of IKS or Oxford score or loss of independence. DISCUSSION: Total knee arthroplasty can be considered for peri-articular fracture of the knee in osteopenic geriatric patients. Although surgical revision was less frequent than after osteosynthesis and resumption of weight-bearing was immediate, autonomy was still impaired. Mortality was comparable to other reports. LEVEL OF EVIDENCE: IV, retrospective study.

Tantalum cones and bone defects in revision total knee arthroplasty.

Management of bone loss is a major challenge in revision total knee arthroplasty (TKA). The development of preformed porous tantalum cones offers new possibilities, because they seem to have biological and mechanical qualities that facilitate osseointegration. Compared to the original procedure, when metaphyseal bone defects are too severe, a single tantalum cone may not be enough and we have developed a technique that could extend the indications for this cone in these cases. We used 2 cones to fill femoral bone defects in 7 patients. There were no complications due to wear of the tantalum cones. Radiological follow-up did show any migration or loosening. The short-term results confirm the interest of porous tantalum cones and suggest that they can be an alternative to allografts or megaprostheses in case of massive bone defects.

Poor short-term outcomes after computer-assisted rotating-platform total knee arthroplasty with a deep-trochlear-groove femoral component: analysis of 19 patients.

BACKGROUND: Congruent rotating tibial plateaus are designed to minimise wear after total knee arthroplasty (TKA). The Score™ prosthesis has a congruent rotating tibial plateau, a deep trochlear groove, and uses a computer-assisted navigation system for ligament balancing. Although this prosthesis is widely utilized, no accurate data on outcomes are available. HYPOTHESIS: The innovative features of the Score™ prosthesis, most notably patellar replacement with a highly constrained femoral component, do not jeopardize implant survival. PATIENTS AND METHODS: In a pilot study, we retrospectively evaluated outcomes of 19 patients treated with Score™ knee replacement between February and October 2006 (mean age, 66.8 years; range, 58-82 years). The evaluation criteria were the International Knee Society (IKS) scores and prosthesis survival rate estimated using Kaplan-Meier plots with failure defined as revision need to change the prosthesis. RESULTS: Mean follow-up was 35.3 months. The IKS knee score increased from 27.4 (5-60) preoperatively to 81.4 (45-99) at last follow-up (P<0.0001). Mean mechanical axis was 181.2° (180-186°), with 16 between 180° and 183°. Revision surgery was required in five cases (for patellar complications with combined motion-range limitation in flexion (<90°) and extension (5-20°) in three cases, isolated motion-range limitation in one case, and recurvatum deformity with instability in one case). Prosthesis survival was 82% (73-91%) after 24 months and 65% (51-78%) after 44 months. DISCUSSION: The deep trochlear groove femoral component resulted in patellar complications, which were the most common reasons for revision surgery, together with motion-range limitation and instability possibly related to improper use of the navigation system. This small retrospective case-series study showed an unusually low prosthesis survival rate probably related to the implant design. We no longer use the Score™ prosthesis, despite the availability of a dedicated navigation system, and we recommend careful monitoring of patients who have this prosthesis. LEVEL OF EVIDENCE: Level IV, retrospective study.

Severe corrosion after malpositioning of a metallic head over the Morse taper of a cementless hip arthroplasty. A case report.

Morse tapers are frequently used in total hip replacement to achieve precise adjustment of lengths and femoral offset. Mechanically, they do not raise any specific problems so long as strict positioning requirements are observed and elements from different manufacturers are not mixed together. We report a case in which the implant induced unexplained pain at 2 years, in relation to a defective fit between the metallic head and the Morse taper. Asymmetric partial fit of the head onto the taper was detected on control X-ray and was implicated as causing metallosis due to excessive release of metal debris from the Morse taper. Revision required femoral stem exchange because of the damage to the Morse taper as well as replacing the cup with new metal-metal bearings. Evolution was favorable at 3 years' follow-up. Most hip replacements include a Morse taper; the present clinical case is a reminder that strict positioning rules are to be respected, without which corrosion and wear may lead to mechanical failure.

[Avascular necrosis of the capitate: a case report and a review of the literature]. / Ostéonécrose aseptique du grand os et traitement : à propos d'un cas et d'une revue de la littérature.

We report the rare case of a patient with an avascular necrosis of the proximal part of the capitate, with a review of the literature. The patient was treated by a resurfacing prosthesis of the proximal part of the capitate. At 22 month of follow up, the patient had a good functional result. Resurfacing prosthesis is a good therapeutic option in case of proximal capitate avascular necrosis when there is no more place for conservative surgery.

[Combined carpometacarpal dislocations, hand lesions and fractures of the two bones of the forearm: a report of two cases]. / Luxations spatulaires et lésions associées de la main et des deux os de l'avant-bras. A propos de deux cas.

The authors report two cases of complete dorsal carpometacarpal dislocations associated with lesions of the hand and the two bones of forearm. These dislocations are rare, and their clinical and radiological diagnosis is difficult. These cases are original through the association of carpometacarpal dislocation with lesions of the two bones of forearm. They demonstrate the need to stress the importance of a complete evaluation of the patient. Treatment must be immediate and begin with the osteosynthesis of the proximal lesions to avoid any irreducibility. These elements will determine the functional outcome.