The presence of retained metalwork, previou fractures or osteotomies makes TKA surgery challenging. Obstructed intramedually canals can produce difficulty with the use of IM instrumentation whilst the altered alignment can result in problematic soft tissue balancing.

We present a series of 35 patients with deformity who underwent a successful TKA.

Between July 2003 and January 2006 35 patients were operated on between 3 centres. All had extraarticular deformities in either the femur or tibia due to previous fractures or exposure to surgery. All underwent TKA surgery using an image free computer navigation system and extramedullary TKA instrumentation. All patients underwent pre-op and post-operative long eg alignment films.

The pre-operative long eg films showed an alignment of 16 degrees varus to 18 degrees of valgus. Post-operative alignment ranged from 3 degrees varus to 4 degrees valgus. The femoral component position ranged from 88-91 degrees from the mechanical axis whilst the tibial component position ranged from 89-92 degrees from the mechanical axis of the limb.

Total knee arthroplasty in the presence of extraarticular deformity is fraught with problems in regaining limb alignment and soft tissue balancing. This is the largest combined series of patients in which the same navigation system has been used to provide extramedullary alignment and cuts resulting in excellent component positioning and post-operative alignment. We recommend the routine use of computer navigation in these difficult cases.

Introduction: Computer assisted-surgery (CAS) brings in a great precision to the alignment of the components and the axis of the extremity in total knee arthroplasty (TKA). On the other hand, even though the MIS technique exerts a lesser aesthetic impact, favours the faster recovery of the patient and preserves the soft parts better, it can also lead to mistakes in the alignment of the implant due to the deficient visualization. Adding CAS to MIS may solve this potential complication.

Objective: To compare the alignment of the components with regard to the mechanical axis in four TKA groups (standard surgery, MIS surgery, standard surgery with CAS, and MIS with CAS).

Materials and Methods: Prospective and randomized study. 100 patients with Alhbäck degree III primary degenerative osteoarthritis of the knee and less than 10° of varus-valgus were included. The patients were randomly distributed in 4 groups of 25 patients each, and the same surgeons performed the surgery. Two CT surviews were performed on every patient, one preoperatively and one during the immediate postoperative period, including hip and ankle, where the femoral, tibial and femoro-tibial axis measurements were carried out.

Results: Mean age was 71.63 years (SD 6.68); 81 % of patients were women. Preoperative mean varus was of 7.57° (SD 1.10). No significant differences were found in the femoro-tibial alignment nor in the components with regard to the mechanical femoral axis between the four groups (Table 1). Nevertheless, significant differences in favour of the MIS-CAS technique group for the alignment of the tibial component with regard to the mechanical tibial axis were found.

Conclusions: The MIS technique allows for a well-aligned TKA implantation. Nevertheless, when CAS is coupled with this technique, the alignment of the tibial component is improved. It is possible for the association of MIS and CAS to become a true advance in TKA implantation.

Background: Measurement of quality of life (QOL) and functional status provides important additional information for priority setting in health policy formulation and resource allocation. Our aim was to define the differences in the health-related quality of life between hip artroplasties with cementation and without cementation. The last objective was to reunite evidences on the advantages and disadvantages of both systems of hip arthroplasty fixation. Methods: We analyzed a random sample of patients in surgical waiting list of total hip arthroplasty, between 65 and 75 years, divided in two groups of 40 patients who received a cemented or uncemented THA, respectively. We compared the pre-operative characteristics and at a year after operation changes in the Nottingham Health Profile (NHP) and SF-12 self-administered questionnaires. We also performed the specific Harris hip score. To make the different scoring systems comparable, all scores were transformed to a 0-to 100-point scale, with 100 points indicating best health. Differences among these groups were compared using the Mann-Whitney U test. Results: All patients increased their QOL scores. Both groups had similar QOL scores before surgery. At 1 year, patients with the uncemented prosthesis had slightly higher scores for energy, pain, and emotional reaction. Changes in QOL scores were, however, very similar. Conclusions: The use of an uncemented prosthesis does not impair early outcome.

Introduction.- Some of the recommended alternatives to increase the cementless acetabular cups stability are the plasma sprayed porous coated and HA and the press-fit impaction. The incorporation of three peripheral fins improves final fixation avoiding micromotion at the immediate post operative period. From 1992 we have implanted 4068 cups, the majority of them in primary cases (78%). The rest 22% in revision cases.

Cup characteristics: hemispheric with fins to improve prumary fixation and HA coating; ring-long ystem in common with other Biomet models, reason why liner are interchangeables.

Material and methods.- 4.068 Bihapro cups (Biomet-Merck) were implanted at a multicenter study in three Hospitals, adjoined to the University, between 1992 and 2003. This is a press-fit model with a porous surface coated with HA and three peripheral fins to improve primary fixation and also dome holes to allow the use ob bone screws.

Prymary indication: osteoarthritis (76%), AVN (7%), fractures (8%), dysplasias (3%), rheumatoid arthritis (6%). Surgical approach: lateral (49%), posterolateral (34,2%), anterior (16,8%). Prophylaxis: antitrombotic (LMWH), antibiotic (1st generation cephalosporins), heterotopic ossification (indomethacin).

Results.- Results. 24 patients showed dislocation and 47 % had some degree of periarticular ossification one year alter surgery; the approach used did not show significative differences. The survival study was done using Kaplan-Meier’s curve. The end-point for failure in this study was the need to perform aesptic revision surgery; being the survival at 9 years of 99.49 % (CI 95 % 99.08 – 99.90). Seven cases needed revision surgery (0.3 %); two cases for migration of the cup and five cases for iterative dislocations.

Conclusions.- Acetabular cups with Plasma Spray Porous Coating in combination with HA, results stable at mid term. The supplementary fixation of the three peripheral fins avoids micromotion optimizing long-term fixation.

Background: Total knee replacement (TKR) failure is usually due to alignment, stability or fixation defects. Objective: To quantify the loads distribution using an absorptiometric method with two different tibial stems.

Methods: We analyzed 20 patients with cemented TKR, in two groups: one of them cylindrical and the other with cruciform stem. We studied the periprosthetic bony density evolution in three areas: under the stem, internal and external baseplate. We performed dual-energy x-ray absorptiometric (DEXA) measurements at 2, 3 and 7 years of follow-up.

Results: The evolution of the bony density under the internal baseplate to 2 and 3 years decreased from 0.920.20 to 0.900.19 g/cm2; under the external baseplate changed from 0.970.36 to 0.970.38 and under the stem raised from 1.050.25 to 1.080.26 in the cylindrical group. In the cruciform group, under the internal baseplate decreased from 0.750.08 to 0.710.05, under the external one decreased from 0.890.01 to 0.850.07 and under the stem changed from 1.060.06 to 1.040.29.

Comparing only the cylindrical subgroup (three missing patients), the DEXA measurements at 2, 3 and 7 years of follow-up were: 0.88, 0.84 and 0.80 g/cm2 under the internal baseplate; 0.79, 0.78 and 0.77 under the external one, and 0.99, 0.96 and 0.99 under the stem.

Conclusions: Loss of bony density is observed progressively after TKR. Comparativily, the diminution is greater for the cruciform stem. The internal compartment is more affected.

Aims: To study the utility of a computer assisted orthopaedic surgery (CAOS) wireless system (navigator) in Total Knee Arthroplasty (TKA). Methods: Randomised prospective study. A sample of 40 TKA patients was randomised in two groups: CAOS was used in 20 of them. In the other group standard technique with manual alignment was performed. Femoral angle (formed between the femoral mechanical axis and the femoral component), tibial angle (formed between the tibial mechanical axis and the tibial platform) and femorotibial angle (formed between femoral and tibial mechanical axes) were measured from Computed Tomography Surviews taken in the immediate postoperative period. Results: In the standard group (without navigator) the femoral angle mean was 91.7° (ranged 90 to 94°). Tibial angle mean was 90.2° (87°–95°) and femorotibial angle mean was 175.9° (172°–180°) showing a slight prevalence of varus deviation of the extremity mechanical axis. In the group with navigator the femoral angle mean was 90.2∞ (87–93°), tibial angle mean 89.6°(85°–93°) and femorotibial angle mean 179.2° (177°–182°). There were statistically significant differences between groups for the femoral angle (p=0.001), and the femorotibial angle (p < 0.001). An ideal femorotibial angle (180±3°) was achieved for all the patients of the CAOS group but only 9 patients of the standard technique group reached this objective (p< 0.001). Conclusions: The use of CAOS for TKA favors the implant placement in a position nearer to the ideal mechanical axis.