Effect of flexion/extension splintage post total knee arthroplasty on blood loss and range of motion -- a randomised controlled trial.

Previous published research has shown promising results with flexion splinting post total knee arthroplasty. Before instituting this practice, we conducted a randomised controlled trial to confirm any benefits over splinting in extension. Five patients were recruited into the trial. 5 were excluded. The flexion group consisted of 49 patients who had their knee placed in 70 degrees of flexion over an inactive CPM machine for 24 h post operation. The extension group consisted of 46 patients who were splinted in full extension for the first 24 h post operation. We assessed post-operative day 1 drain volume, haemoglobin and haematocrit, blood transfusions, duration of inpatient stay, range of motion and complications within 6 weeks of surgery. There was no significant difference between the two groups among any of the outcomes measured. As such, we have been unable to demonstrate any benefit with splintage in flexion post total knee arthroplasty and have not adopted it as part of our post-operative management.

Migration pattern of a short femoral neck preserving stem.

UNLABELLED: The CFP stem represents a short collared neck-retaining stem with very proximal metaphyseal anchoring along the calcar combined with up-to-date metallurgy. Despite theoretical advantages, the stability and clinical outcome are unknown. We prospectively measured the migration pattern of this new stem and cup. Twenty-six patients (26 hips) with a mean age of 54 years (range, 40-66 years) underwent THA and were followed for 2 years with radiostereometry, radiographs, and clinical scores. The stem showed some early retroversion (mean, SEM 0.6 degrees, 0.3), but stabilized before 1 year. Subsidence (0.05 mm, 0.06) and varus-valgus tilting (0.03 degrees, 0.01) were low. We observed no bone loss in the calcar region. Factors related to patients, implant design, and implantation did not predict migration patterns. The two-dimensional wear of the ceramic/conventional articulation was 0.09 mm at 2-24 months. The low migration of this short neck preserving stem suggests a favorable long-term outcome but longer followup is needed to substantiate this prediction. This design might become an alternative to standard stems and hip resurfacing. LEVEL OF EVIDENCE: Therapeutic Level IV. See The Guidelines for Authors for a complete description of levels of evidence.

A constrained acetabular component for recurrent dislocation.

We treated 34 patients with recurrent dislocation of the hip with a constrained acetabular component. Roentgen stereophotogrammetric analysis was performed to assess migration of the prosthesis. The mean clinical follow-up was 3.0 years (2.2 to 4.8) and the radiological follow-up was 2.7 years (2.0 to 4.8). At the latest review six patients had died and none was lost to follow-up. There were four acetabular revisions, three for aseptic loosening and one for deep infection. Another acetabular component was radiologically loose with progressive radiolucent lines in all Gruen zones and was awaiting revision. The overall rate of aseptic loosening was 11.8% (4 of 34). Roentgen stereophotogrammetric analysis in the non-revised components confirmed migration of up to 1.06 mm of translation and 2.32 degrees of rotation at 24 months. There was one case of dislocation and dissociation of the component in the same patient. Of the 34 patients, 33 (97.1%) had no further episodes of dislocation. The constrained acetabular component reported in our study was effective in all but one patient with instability of the hip, but the rate of aseptic loosening was higher than has been reported previously and requires further investigation.

A comparison of three methods of wound closure following arthroplasty: a prospective, randomised, controlled trial.

We carried out a blinded prospective randomised controlled trial comparing 2-octylcyanoacrylate (OCA), subcuticular suture (monocryl) and skin staples for skin closure following total hip and total knee arthroplasty. We included 102 hip replacements and 85 of the knee.OCA was associated with less wound discharge in the first 24 hours for both the hip and the knee. However, with total knee replacement there was a trend for a more prolonged wound discharge with OCA. With total hip replacement there was no significant difference between the groups for either early or late complications. Closure of the wound with skin staples was significantly faster than with OCA or suture. There was no significant difference in the length of stay in hospital, Hollander wound evaluation score (cosmesis) or patient satisfaction between the groups at six weeks for either hips or knees. We consider that skin staples are the skin closure of choice for both hip and knee replacements.

Cross-linked polyethylene and bisphosphonate therapy for osteolysis in total hip arthroplasty: a case report.

A 39-year-old woman underwent bilateral total hip arthroplasty with conventional, ethylene oxide-sterilised liners when she was a subject in a radiostereometric analysis study. Within 2 years she had rapid polyethylene wear with aggressive, asymptomatic, and periprosthetic osteolysis on both sides. Oral alendronate therapy halted the progression of osteolysis over a year and revision to cross-linked polyethylene liners was then undertaken while one stem was curettaged and the other revised. Radiostereometric analysis revealed a 96% reduction in wear rate over 2 years with the cross-linked liners. On stopping alendronate treatment, aggressive osteolysis recurred on the curretaged but not on the revised femur.

Bone cement with reduced proportion of monomer in total hip arthroplasty: preclinical evaluation and randomized study of 47 cases with 5 years' follow-up.

Bone cement with reduced amount of monomer and low curing temperature may improve implant fixation due to reduced toxicity. We analyzed the mechanical, chemical and thermal properties of such a cement (Cemex Rx) using Palacos R as control. The in vivo performance of the 2 cements was also evaluated in a prospective randomized study of 47 hips, where either of the cement types was used to fixate Lubinus SP2 prostheses with the stem made of titanium alloy. Cemex Rx had a reduced tensile strength, probably because this cement was manually mixed, as recommended by the manufacturer. A standardized labor tory test showed lower curing temperature for Cemex, but measurements at 37 degrees and with prechilled Palacos R and Cemex Rx, as in clinical work, showed no difference. In the clinical study radiostereometric measurements of cup and stem migration showed similar values in the 2 groups up to 5 years after the operation. The cement mantle was stable in both groups, but the stems migrated similarly inside the cement mantle regardless of the type of cement used. Proximal wear was low (0.04-0.05 mm/year) and tended to be lower in the Cemex group (p = 0.02). Aluminum and vanadium levels in serum increased 5 years after the operation, but no difference was noted between the 2 groups. Collagen markers (PICP, ICTP) showed similar increases in bone turnover 6 weeks and 6 months after operation in both groups.

Cytokine levels in synovial fluid from hips with well-functioning or loose prostheses.

We analysed synovial fluid from 88 hips, 38 with osteoarthritis and 12 with well-functioning and 38 with loose hip prostheses. The levels of TNF-alpha, IL-1beta (71 hips) and IL-6 (45 hips) were measured using the ELISA technique. Joints with well-functioning or loose prostheses had significantly increased levels of TNF-alpha compared with those with osteoarthritis. Hips with aseptic loosening also had higher levels of IL-1beta but not of IL-6 compared with those without an implant. The levels of TNF-alpha and IL-1beta did not differ between hips with stable and loose prostheses. Higher levels of TNF-alpha were found in hips with bone resorption of type II and type III (Gustilo-Pasternak) compared with those with type-I loosening. The level of cytokines in joint fluid was not influenced by the time in situ of the implants or the age, gender or area of the osteolysis as measured on conventional radiographs. Our findings support the theory that macrophages in the joint capsule increase the production of TNF-alpha at an early phase probably because of particle load and in the absence of clinical loosening. Since TNF-alpha has an important role in the osteolytic process, the interfaces should be protected from penetration of joint fluid.

Increased migration of the SHP prosthesis: radiostereometric comparison with the Lubinus SP2 design in 40 cases.

40 patients with primary arthrosis were randomized to receive either a cemented SHP (Scientific Hip Prosthesis) or Lubinus SP2 prosthesis. At 2 years radiostereometric measurements showed increased proximal migration (0.4/0.2 mm; p = 0.02) and more proximal wear (0.3/0.1 mm, p = 0.01) of the SHP socket. The SHP stem also subsided (-O.6/-0.1 mm, p<0.001) and rotated more into retroversion (2.6/0.3 degrees ) than did the SP2 design. This subsidence mainly occurred inside the cement mantle in 17 of 18 cases (13 SHP, 4 SP2), where this type of motion could be measured. The changes in bone mineral density evaluated with DEXA and the clinical results did not differ between the 2 groups. The subsidence of the SHP stem is the most pronounced so far recorded with radiostereometry in stems without a completely polished surface. This subsidence and the rotational instability imply a substantial risk of abrasive wear and increased stresses in the cement mantle.

Fixation and metal release from the Tifit femoral stem prosthesis. 5-year follow-up of 64 cases.

We stratified the fixation of the femoral component in 64 hips with degenerative joint disease into 3 groups, cemented (C), proximal hydroxyapatite coating (HA) or proximal porous coating (P). All implants had the same basic design and were made of TiAIV alloy. The migration of the implants was assessed by radiostereometry. After 5 years, the mean subsidences in the cemented and porous-coated groups were 0.16 and 0.31 mm, whereas the HA-coated implants displayed a mean proximal migration of 0.1 mm. 7 stems (2 C, 1 HA, 4 P) showed a continuous subsidence (> 0.25 mm) between the 2- and 5-year follow-up. 1 porous-coated stem was revised after the 2-year follow-up, because of pain and implant failure (previously reported) and 1 cemented stem was revised after 5 years because of pain and osteolysis. In a subset of patients, all with a femoral head made of aluminum oxide, the levels of metal were determined using atomic adsorption spectrometry. Subsidence of the stem between the 2- and 5-year follow-up was associated with increased levels of aluminum in the blood at 2 years. Generation of metallic particles from abrasive wear of the stem followed by third body abrasion of the ceramic femoral head could be one explanation of this finding. 5 hips which had shown high levels of titanium and aluminum in joint fluid at the 2-year follow-up displayed increased subsidence and developed proximal radiolucencies or osteolysis at the 5-year follow up. One of these was the cemented hip which was subsequently revised.

Migration, stem shape, and surface finish in cemented total hip arthroplasty.

In many recent publications it was suggested that the amount of early subsidence of a femoral stem in total hip arthroplasty is indicative for later revision. In this article it is argued that stems can be designed according to alternative objectives, resulting in different shapes and surface roughness, each producing its own characteristic postoperative subsidence pattern. It was investigated whether these inherent subsidence patterns can be estimated in preclinical testing. For that purpose two stems, both without a collar, relying on cement fixation only, were compared regarding their stress transfer, migration, and induced micromotion behavior. Finite element analysis, cyclic bench testing of substitute bone reconstructions, and clinical radiostereophotogrammetric analysis were applied. The stems investigated were the Exeter, which is assumed to be a force closed fixation design, relying on subsidence under load as a method of maintaining stability, and the SHP, as a shape closed fixation design, meant to be contained by the cement mantle. Both designs were true to their design concepts in the analyses, in the sense that migrations and micromotions of the Exeter stems far exceeded those of the SHP stems. It was found that preclinical studies such as finite element analysis or bench tests give reasonable indications of in vivo postoperative behavior. It is concluded that early clinical migration values should be considered relative to stem shape and surface finish, when prediction of later revision probability is the issue.

Radiostereometry of hip prostheses. Review of methodology and clinical results.

Radiostereometric analysis is a science that enables reliable measurements to be made from radiographs. The method involves several steps including insertion of spheric tantalum markers, radiographic examinations, measurements of radiographic films, and calculations of three-dimensional movements. The precision of the method corresponding to the 99% significance interval varies between 0.15 and 0.6 mm and 0.3 degree and 2 degrees when applied to total hip replacement depending on the technique used. Measurements of implant micromovement during 1 to 2 years after surgery have proved to be of value to predict later clinical failure because of aseptic loosening and revision. Subsidence of the femoral stem or proximal migration of the acetabular cup between 1 and 2 mm has indicated increased risk of early or intermediate term revisions in those prosthetic designs studied so far. Minimum early migration has been recorded for clinically well documented nonpolished stems and polyethylene cups, which probably is one explanation for their long term success. This small amount of early micromotion also has been found in porous coated and screw fixated press fit cups and all hydroxyapatite coated designs hitherto studied. As a first step in a clinical evaluation of new implants or surgical techniques, the predictive value of radiostereometric analysis measurements can be used to reduce the number of patients exposed to the potential risk of clinical failure.

Migration and wear of hydroxyapatite-coated press-fit cups in revision hip arthroplasty: a radiostereometric study.

Screw-fixated and hydroxyapatite-coated press-fit cups were studied using radiostereometry in 29 revision and 14 primary arthroplasties. The acetabular defects in the revision cases varied from none to type 3 (wall defects) according to Gustilo-Pasternak. Morsellized allograft was used in 25 revisions. Nine of these cups rested on less than 50% living bone. After 2 years, the mean migration in the revised group reached 0.36, 0.21, and 0.49 mm in the horizontal, longitudinal, and anteroposterior (AP) directions. The mean rotations varied between 0.5 degrees and 0.7 degrees depending on direction. The primary implants displayed smaller mediolateral migration and AP tilt. The mean proximal wear rate for the whole group was 0.11 mm/y. A central gap on the postoperative AP view implied less migration. The size of the preoperative bone defects or amount of bone-graft used had no influence on the migration. Despite extensive use of morsellized allograft, this implant displayed the smallest migration so far reported in revision hip arthroplasty.

Migration of porous press-fit cups in hip revision arthroplasty. A radiostereometric 2-year follow-up study of 60 hips.

The migration of 60 press-fit cups fixed with screws was evaluated by radiostereometric analysis for 2 years in 57 patients revised because of aseptic loosening. The mean proximal migration of the cup center increased continuously up to 0.36 mm (range, 0.0-1.6 mm), whereas the migration in the other directions reached a level at 0.3 to 0.4 mm after 6 months. Mean rotations of less than 1 degree were recorded. Factors influencing motions were cup size, use of bone-grafts, and position of the cup center in the vertical and horizontal directions. Compared with previous stereoradiographic studies of cemented revisions, the migration of the press-fit cup was smaller, however, still higher than previously reported for uncemented cups of the same design used in primary surgery.