Calcification and ossification have been described in artery wall in pathologic conditions and aging. We previously described the use of cryopreserved arterial allografts as membranes for guiding bone regeneration. We hypothesize that artery is as good as synthetic membranes (e-PTFE, gold-standard in guided bone regeneration) due to the osteogenic potential of cells from its medial layer.

A comparative study was made creating 10 mm mid-diaphyseal radial defects in 15 New Zeland rabbits (30 forearms): 10 defects were covered with an e-PTFE membrane and 10 defects with no membrane (control group). Studies: X-rays, CT, MR, morpho-densitometric analysis, electronic and optical microscopy.

To demonstrate the cellular arterial stock, cryopre-served and fresh rabbit thoracic aorta specimens were studied. Medial layer was isolated and cultured as explants in normal medium. Cells were harvested and added to a 3-D scaffold based on plasmatic albumin in osteogenic medium. Immunocitochemical study was made. Radial defects surrounded by cryopreserved arterial membranes showed total regeneration in nine of 10 defects versus seven of 10 defects in e-PTFE group (no statistically significant differences were detected between them). No tissue layer was found between bone and artery while a connective tissue layer was observed between e-PTFE and bone. Neither radiological nor histological healing were detected in the control group.

Cells cultured had smooth muscle features as they showed immunofluorescence with anti-smooth muscle alpha-actin, anti-calponin and anti-vimentin antibodies. When cells were added to a 3-D matrix, they showed chondro and osteogenic differentiation, as they stained positive for types II and X collagen, alkaline phosphatase and von Kossa.

Although no statistically significant differences between artery and e-PTFE groups were detected, histological and cellular findings suggest a superiority of cryopreserved arterial allografts when compared with synthetic membranes of e-PTFE, with a contribution of the cellular stock of the medial layer in the healing process.

Introduction: Instability of THR is a problem both for the patient and the surgeon. Its frequency varies from 3 to 20% in multioperated patients. When the cause is known treatment usually gives good results and one way of preventing dislocation is to increase the size of the prosthetic head. The cause for instability is multifactorial and sometimes the patients have predisposing factors: muscular weakness or neurological alterations that determine the need for constrained and bipolar cups.

Materials and methods: Constrained cups capture the prosthetic head preventing dislocation and studies have been published with widely differing results. The bipolar cup introduced by Busquet is based on a metal cup coated with hydroxyapatite that is fixated by means of 2 plots to the ischium and the pubis. The polyethylene insert captures a head of 22.2 or 28 mm. Dislocation, when it takes place, is between the metal cup and the insert, and a force much greater than that needed to dislocate a head of 22.2 or 28 mm in diameter is needed.

Results: In a multi-center study carried out on 238 bipolar cups, Leclerc reports a 3.3 % failure rate. Philippot using 106 bipolar cups, reports no dislocation and a survival of 94.6% at 10 years. Our personal series comprised 75 cases, (54 primary and 21 revisions) with only one episode of dislocation due to significant trauma.

Conclusions: The bipolar cup can be used in primary and revision surgery and is effective in decreasing dislocations in high-risk patients and is our option of choice in patients with neuromuscular alterations or multiple surgeries.

Purpose: To assess the performance of a constrained liner in an unstable hip prosthesis.

Materials and methods: This is a retrospective study of 66 hip prostheses implanted in 66 patients by means of the same constrained cup (Lefevre, Lepine Group, France). The cup was implanted into 15 primary prostheses and 51 revision ones in order to treat recurrent dislocations (10 cases) or to prevent dislocations (56 cases with a deficit of the periarticular musculature or mental or neuromuscular disorders). The mean age was 76.7 years, 75.7% were female, 53% were operated in the right side and the mean follow up was 30.2 months.

Results: By the time the last review was made, four patients died for reasons not related to their hip surgery. One patient showed a dissociation between the femoral head and the stem at the level of the Morse taper; the head was trapped in the retentive liner and an open reduction was needed to replace the existing prosthetic head by a new one with a long neck. Another patient had a prosthetic infection that was treated by means of a two-stage replacement. Radiolucent lines were observed in de DeLee’s zone 1 in 1.5% of patients, in 3% the lines were in zone II and in 3% they were in zone. However, according to Hodgkinson’s radiographic criteria, no cups were loose.

Conclusions: Although retentive cups do address hip instability, the various cases of failure that have occurred, the appearance of radiolucencies and the concerns about their long-term fixation suggest that their use should be carefully weighted.

Purpose: To assess the use of cortical allografts (bone plates?) in hip replacement surgery.

Materials and methods: This is a retrospective study of 43 bone plates in 36 hip prostheses. In 18 cases they were implanted to treat a periprosthetic fracture (an associated replacement of the femoral component was performed in 5 cases) and in 18 they were implanted to replace a loosened stem in a hip with large bone defects. Standard long uncemented stems were implanted in 7 cases and standard cemented stems associated with morselized compacted allografts were implanted in 16 cases. 14 patients were only given bone plates and in 22 these bone plates were associated to a metal plate. The mean age was 69.1 years (range: 38–82). 61.1% were female, 18% were implanted in the right side and the mean follow-up was 45.4 months.

Results: At the time of the last review, three patients had died but for reasons not related to their hip surgery. Transient sciatic nerve palsy was observed in one patient, prosthetic dislocation in three cases (two of them were successfully treated with bracing and the other had to be given a constrained cup), there was an infection (treated with a two-stage replacement) and two re-fractures (after 3 and 13 months) treated with a new osteosynthesis with a bone plate associated to a metal plate. All the fractures healed and the imaging tests showed an integration of the bone plate with the host bone with no signs of prosthetic loosening.

Conclusions: Cortical allografts can fulfill two functions: a mechanical one (they behave as if they were a plate) and a biological one (they increase bone stock on integration).

Aims: Clinical and radiographic comparison between a fixed polyethylene prostheses and mobile bearing design. Methods: Prospective study in 147 tricompartimental cemented cruciate-retaining prostheses (Interax, Stryker- Howmedica-Osteonics): 90 conventional fixed polyethylene and 57 mobile bearing (antero-posterior slide and rotation over an axis in the medial plateau). No differences in preoperative age, sex, range of motion, deformity, rheumatoid arthritis or osteo-arthritis, and Ahlback stage. Results: At 1, 6, 12 and 24 months there were no differences between both groups (p> 0.05) in femorotibial angles, radiolucencies, duration of surgery, pain at rest or walking, stairs, arise from chair, walking ability, range of motion, supports (cane or crutches), complications and score of the American Knee Society. Conclusions: With 2-year follow-up there are no differences in clinical or radiographic results between fixed and mobile bearing knee prostheses. Further investigations with long-time follow-up are mandatory in order to determine differences and advantages in polyethylene wear or implant survival.

Aims: To determine whether the use of Biphasic Calcium Phosphate (BCP) plus local autogenous graft modifies our clinical results and fusion rate, in comparison with iliac crest graft alone. Methods: Prospective and nonrandomized study. 40 patients were operated on with pedicle instrumentation and posterolateral fusion. Degenerative lumbar disease was the etiology. 25 patients had one level fusion and 15 two or more. Minimum follow-up: 1 year. 15 patients were smokers (17.4 cig/day). The Oswestry disability index at 0, 3, 6 and 12 months was filled in to see the evolution and final clinical result. To evaluate the fusion, X-ray criteria were used. Results: Oswestry test changed from 63,8 to 16,4 at the end of the study. 3 patients did not achieve fusion (7,5%), none of them smokers. Up to date we have been working with the same idea but trying to increase the fusion rate by adding bone marrow to BCP and grafts. The initial results are very encouraging. Conclusions: We have no difference in our non-union rate between previous historic register and the new technique.

Similar clinical results were obtained but the proportion of excellent/good has improved with iliac crest preservation.

Aims: Clinical and radiographic evaluation of retinacular lateral releases using an arthroscopic approach, for anterior knee pain in cases with slight patelar axial malposition Methods: Prospective study in 34 patients. Evaluation according to the Insall clinical score, patient opinion, and change in radiographic angles and index from pre-operative to post-operative. Results: Postoperative clinical score (Insall 1983): 82% excellent; 6% good; 6% poor; 6% bad. Angular values: patelar index (Cross 1976) of 7,1 and sulcus angle (Brattstrom 1964) of 139,6∞. Radiographic correction: from 15,7 to 17,9 in patello-femoral angle (Laurin 1978); from −5,6 to −5,3∞ in congruency angle (Merchant 1974); and from 1,37 to 1,12 in patello-femoral index (Laurin 1978). Conclusions: Clinical results, patient satisfaction, and radiographic correction of congruency angle, patello-femoral angle and patello-femoral index make justifiable the use of arthroscopic lateral releases in the treatment of selected cases of patello-femoral pain.

Introduction and Objectives: This is a prospective analysis of clinical and radiographic outcomes of total hip prosthesis with alumina-on-alumina friction coupling implants performed at two hospitals.

Materials and Methods: This study analyzes 60 prostheses with alumina-on-alumina friction coupling (Ceraver-Osteal) (May 1999-May 2002). The Cerafit cup was used in association with 32 Multicone-HAC stems and 28 Anatomic-HAC. Of these cases, 36 were male, and 24 were female, with average age being 47.05+/−12.60 years. Mean follow-up time was 2.3 years. There were no lost or revised cases. Radiographic analysis was done according to Johnston et al., and wear was assessed using the Sychterz method in a special computer program (Auto-CAD R14).

Results: All cases had good clinical and radiographic outcomes. There were no revisions or loosening of the implants. There was one dislocation and one intraoperative fracture, which were both treated by conservative means. There were no infections. The distance between the centres of the femoral head and the cup on the initial radiograph (position zero) was 2.49+/−0.70mm. This measurement stayed constant with time, and no changes were observed associated with so-called early wear or initial seating. Mean wear with respect to a reference of position zero was 0.0184+/−0.0187. This figure is below the error level of the measuring system and thus is not measurable.

Discussion and Conclusions: The alumina-on-alumina prosthesis (Ceraver) yields positive clinical and radiographic results at 4 years. Even though the alumina partially distorts the radiographic image, no evidence of early wear due to seating of the components was observed at four years of follow up using the Sychterz digitalized method.