[Can the postoperative pain level be predicted preoperatively?]. / Peut-on prévoir, avant l'intervention, l'intensité de la douleur postopératoire?

PURPOSE OF THE STUDY: We searched for factors present preoperatively which could be used to predict the intensity of postoperative pain. MATERIAL AND METHODS: We undertook a prospective study among all patients aged over 18 years who underwent shoulder surgery from January to September 2004 in our unit. The study included 86 patients for which the following data were noted preoperatively: past history of pain, intensity and duration of prior pain, triggering factors, localization, psychological context. The intensity of the postoperative pain was measured on a visual analog scale (VAS); measurements were noted up to 24 hours postop then at one month. Data processing was performed with Statview5.5. RESULTS: Significant postoperative pain was correlated with a prior history of surgical pain, with duration of prior pain, with intensity of preoperative pain, and with depression. DISCUSSION: Significant sustained preoperative pain can favor memory of pain leading to postoperative sensitivization of nociception neurons. Intense postoperative pain can favor the development of refractory chronic pain. CONCLUSION: Significant postoperative pain can be expected in the following situations: pain after prior surgery, presence of chronic pain sustained for more than six months, intense preoperative pain, state of depression.

[Metaphyseal and diaphyseal modular femoral stems implanted without cement]. / Modularité métaphyso-diaphysaire et tiges fémorales sans ciment.

PURPOSE OF THE STUDY: We assessed outcome after total hip arthroplasty (THA) using a dual metaphyseal-diaphyseal modular femoral stem with hydroxyapatite coating on the metaphyseal portion only. Implanted without cement, this stem was adaptable to all the anatomic morphotypes defined by the Noble canal flare index. MATERIAL AND METHODS: THA was performed in 116 patients (124 hips), mainly for degenerative joint disease (80% for dysplasia). Mean age was 61.2 years. Follow-up was 6.9 years (72-108 months). RESULTS: There were no preoperative complications excepting 3 cases of neck fissuration without clinical consequence. There was no trochanteric fracture. We had two early and one late dislocations. The Postel Merle d'Aubigné score improved from 8.09 to 17.27. Clinical outcome was not influenced by patient age, weight or morphotype. Radiologically, signs of bone ingrowth were found in more than 80% of the cases. Lucent lines were seen in only 3 cases. There was a single case of migration. No revision was needed among the cases with ossifications (23%, 22% Brooker I) and no femur revisions were required. There was no mechanical problem involving the metaphyseal-epiphysial junction. DISCUSSION: The dual metaphyseal-diaphyseal modular stem was found to be a safe and effective implant adaptable to all anatomic variations of the femur and providing good primary stability. In our series, 58% of the femurs were "standard" but for one-third of the femurs, the modular stem enabled implantation without cement, particularly in young adults with a dysplasic or funnel-shaped femur. CONCLUSION: The dual metaphyseal-diaphyseal modular stem was found to be most useful for optimizing total hip arthroplasty without cement.

[Impacted acetabular cups]. / Les cotyles impactés.

The failure modes of impacted acetabular cups are: deterioration of the polyethylene insert, disassembly of the modular components, excessive polyethylene wear, severe peri-prosthetic osteolysis. These failures can be explained; solutions are suggested.Primary stability: Screws are pathways for polyethylene debris; impacting elastic cups increases the press-fit effect in order to provide stability without screw fixation.Polyethylene thickness: by increasing polyethylene thickness from a minimum 8 to 10 mm, the risk of insert deterioration is decreased and so too is creep of the core which can induce micromotion between the insert and its metal backing.Liner stability: Tilting of the liner is the most common mecanism of disassembly in two-piece acetabular cups. The solution we suggest is to use a liner with a cylindrical periphery.Polyethylene wear: Excess polyethylene wear in metal backed acetabular cups was reported. Conversly, other authors concluded to no excess wear in impacted cups. This may be due to differences in prosthetic components, as well as patient selection. We noticed no significant wear in our series (0.10 mm per year). Studies are contradictory and it is not obvious that excessive wear in impacted cups has to be feared.Osteointegration is mandatory for obtaining long term stability and is provided by porous coating. The osteoconductive properties of hydroxyapatite have been demonstrated by a large number of studies, including fundamental research, animal experiments and clinical applications. Within a few weeks, hydroxyapatite brings about bonding with the host bone without any intervening fibrous tissue layer. We expect hydroxyapatite-induced osteointegration to prevent particulate migration. Biodegradation of the hydroxyapatite coating occurs after 5 to 10 years. Bone ingrowth later relies on the surface roughness of the substrate.In conclusion, we suggest that the combination of impacted elastic acetabular cups with a thick polyethylene liner and bioactive coating can provide long term durability.

[Poor results in 183 threaded acetabular cups at a mean 7 years follow-up]. / Bilan négatif d'une revue de 183 cotyles vissés au recul moyen de 7 ans.

We reviewed 183 threaded rings at a mean 7 years follow-up. Poor résults are frequent: 34 % had been revised and 50 % have radiographic migration, essentially with proximal migration of the cup. Generally, we reoperated with other cememtless implants. The type of threaded cup does not matter (spheric or conic). Only the duration of follow up seems significant. We think that biomecanical strains, rather than physiology, explain these numerous migrations. We have therefore abandoned threaded cups in favour of porous-coated impacted cups.