In the eye of the beholder: Assessing the water quality of shoreline parks around the Island of Montreal through citizen science.

As a part of the FreshWater Watch project aiming to promote volunteers' water monitoring in 25 cities around the world, St. Lawrence River water quality was characterized at 28 public shoreline parks around Montreal Island, Quebec, Canada. This involved training of 69 citizen scientists by researchers of the Université de Montréal in five one-day sessions. Shoreline sampling yielded 174 data points over three summers (May 2013 to November 2015). Water turbidity, nitrate and phosphate concentrations were measured in situ, together with the thickness and type of beach-cast vegetation, and the relative abundance of different types of beach litter. Data generated by citizen scientists provided 1) an overview of the water quality of the St. Lawrence and Des Prairies rivers around the Island of Montreal, 2) an estimation of the quantity and types of beach-cast aquatic plants and filamentous algae, and 3) novel insights into the distribution of the nuisance cyanobacterium Lyngbya wollei. Overall, half of the sites were classified as "good" being characterized by low turbidity, nitrate and phosphate concentrations, and little deposition of beach-cast vegetation. Lyngbya wollei was found at 57% of the sites, revealing a more frequent occurrence than initially anticipated. The amount of litter recorded along the shoreline was generally small, comprising items related to picnicking (cans/bottles), smoking, and fishing activities in most parks. Wind exposure and rain events explained a significant fraction of the variability in nutrient concentration and turbidity among sites and dates. Shoreline condition assessed from water quality and vegetation data from this study was not correlated, however, with the most serious problem of faecal coliform counts gathered by the City of Montreal. This assessment of the quality and utilization of shoreline parks provides additional information to support planning and management activities of municipalities.

Influence of preoperative factors on the gain in flexion after total knee arthroplasty.

UNLABELLED: Final flexion mobility after a total knee arthroplasty is an important factor in patient comfort. Some patients gain in flexion mobility, others do not. Is it possible to identify the clinical factors related to the patient that predicted the final gain in flexion? MATERIALS AND METHODS: A multicenter retrospective study directed by the Société française de la hanche et du genou (SFHG) was conducted on 1601 cases of total knee arthroplasty that had presented no complications and a minimal follow-up of 2 years. The gain in flexion was assessed by the difference between the preoperative and the final range of flexion. The range of the gain in flexion was tested based on eight factors: age, gender, etiology, body mass index, frontal deformity, preoperative flexum deformity and four levels of preoperative mobility: < 90°, 90°-109°, 110°-129°, and ≥ 130°. RESULTS: A mean gain in flexion of 8.4°±14° was found for the overall series. In 66% of cases, we found an increase of flexion and in 19% a loss of flexion. In cases with BMI higher than 35, varus deformity with an HKA angle<166°, or flessum greater than 5°, the gain in flexion was significantly higher. A significantly different gain in flexion (P<0.0001) was found in the four levels of preoperative flexion: the greatest gain in flexion was found in the "<90°" group, then this gain was less in the next two groups, to become a significant decrease in the "≥130°" group. A decrease in flexion was noted in 51% of the cases in the latter group. Other factors such as age, sex, and etiology had no influence on the gain in flexion. DISCUSSION: After TKA, a gain in flexion was often noted. The amount of gain depended on the preoperative range of flexion: the lower this level was, the more flexion increased. The presence of a varus deformity, morbid obesity, or flessum was associated with greater gain in flexion, even if the final flexion was lower than the mean flexion in the overall population. The search for these factors made it possible to predict a gain in flexion and discuss this with the patient. LEVEL OF EVIDENCE: Level IV. Multicenter retrospective study.

Arthrosis of the knee in chronic anterior laxity.

Arthrosis following rupture of the anterior cruciate ligament has been analysed in two series. The first series was derived from a review of 150 cases of reconstruction of the anterior cruciate ligament with a follow-up of 3 years or more. Arthrosis was seen to have developed in 13.3%. The second series was concerned with 64 cases of unilateral arthrosis treated by upper tibial valgus osteotomy in whom there had been a previous rupture of the anterior cruciate ligament. The 'tolerance interval'--that is the time between the original ligamentous injury and the time of osteotomy--for the development of arthrosis was very variable, ranging in the natural-history cases from 10 to 50 years, with a mean of 35 years. It is important to recognise the radiological signs of the onset of arthrosis. These are osteophytosis of the intercondylar notch, osteophyte formation at the posterior part of the medial tibial plateau, and, in particular, narrowing of the medial joint line with posterior subluxation of the medial femoral condyle, well seen in lateral radiographs whilst standing on one lower limb. Early arthroses, appearing after 10 years, may occur as a 'natural arthrosis', but it develops much more frequently after surgical treatment that had failed to correct anterior laxity and particularly when it had been performed on knees that were already pre-arthrotic. The main factor in arthrosis is anterior laxity measured radiologically by an 'active Lachman' radiograph. Removal of the medial meniscus which in itself, is liable to produce arthrosis, is even more harmful in anterior cruciate laxity since it doubles the degree of anterior subluxation of the tibia seen on unilateral weight-bearing. The development of varus deformity, which characterises progressive arthrosis, has its origin in wear of the posterior part of the medial tibial plateau caused by anterior cruciate laxity. Other factors play an important part such as associated lateral laxity, constitutional genu varum and weakness of the hamstring muscles, which oppose the subluxating action of the quadriceps.

Is unicompartmental-to-unicompartmental revision knee arthroplasty a reliable option? Case-control study.

BACKGROUND: In selected patients with failed unicompartmental knee arthroplasty (UKA), revision UKA is a reliable option and may even provide lower morbidity rates and better functional outcomes compared to revision total knee arthroplasty. MATERIAL AND METHODS: In a multicentre retrospective study of 425 knees requiring revision surgery after UKA, 36 knees were managed with revision UKA. RESULTS: Of the 36 knees, 3 (8.33%) required iterative revision surgery, for aseptic loosening. After a mean follow-up of 8.3 years, the mean IKS knee and function scores were high (93.81/100 and 90.77/100, respectively). DISCUSSION: In carefully selected patients, UKA-to-UKA revision performed according to a rigorous operative technique deserves a role in the surgical strategy for failed UKA. LEVEL OF EVIDENCE: III, multicentre retrospective case-control study.

Total knee replacement following intra-articular malunion.

INTRODUCTION: There is a lack of data on the management of osteoarthritis of the knee associated with intra-articular malunion. The present study sought to analyze and report results of total knee replacement (TKR) in this indication, including complications and technical specificities. HYPOTHESIS: TKR for osteoarthritis of the knee associated with intra-articular malunion entails an elevated risk of complication, with impaired functional results. OBJECTIVES: To test this hypothesis in a retrospective series of 74 cases of osteoarthritis of the knee associated with intra-articular malunion. PATIENTS AND METHODS: A multicenter retrospective series collated the records of 74 patients (mean age, 63 ± 14 years) who underwent TKR for post-traumatic osteoarthritis of the knee associated with intra-articular malunion between 2000 and 2008. Mean trauma-to-TKR interval was 21.8 ± 19 years (range 1 to 56 years). Patients were assessed clinically and radiologically at last follow-up, using the Knee Society score as modified by the Western France Orthopedic Society (Société orthopédique de l'Ouest). RESULTS: At a mean overall follow-up of 4 ± 3 years (range 1 to 9 years), mean knee score improved from 25 ± 12 to 85 ± 7 (P<0.001) and mean functional score from 52 ± 13 to 66 ± 10 (P=0.004). Mean flexion gain was 6°: mean preoperative flexion, 104° ± 28° (10° to 150°), vs. 110° ± 19° (20° to 130°) at follow-up. Nineteen patients (26%) had complications, 13 of which were severe and liable to affect the functional result: three extensor system avulsions, four infections, five cases of stiffness and one of instability. DISCUSSION AND CONCLUSIONS: The present results highlight an elevated rate of complications, with poorer clinical results than those found with osteoarthritis of the knee secondary to constitutional deformity. The initial trauma, with associated hemarthrosis, and sometimes iterative surgery to reduce and fix the initial fracture, induce fibrosis and synovial attachments, leading to stiffness and hindering exposure. The patient should be informed, and warned that postoperative flexion amplitude may be improved but is bound to remain limited, especially in case of initial stiffness. LEVEL OF EVIDENCE: Level IV: non-comparative retrospective study.

Fixed-bearing unicompartmental knee arthroplasty. Patients' selection and operative technique.

Unicompartmental knee arthroplasty (UKA) is designed for patients presenting arthritic wear limited to a single medial or lateral tibiofemoral compartment. The indication is based on strict criteria. Wear must stem from degenerative osteoarthritis or be secondary to aseptic necrosis of the medial condyle. Inflammatory rheumatism is a contraindication. Age and activity level should be compatible with an indication for arthroplasty. The body mass index should be less than 30 kg/m(2). The ligament system must be intact, particularly both cruciate ligaments. Any pre-existing axis deformity should be moderate and the residual axis deformity, after correction of wear with a unicompartmental tibial augmentation spacer, should not exceed 7-10° varus or valgus. These highly restrictive conditions result in the ideal indications for UKA suitable for no more than 15-20% of knee arthroplasty candidates for most surgeons experienced in this procedure. Although the results of certain early series worried potential users, today it can be asserted that recent series whose indications and technique correspond to modern use criteria, have shown results that are as reliable as those of total knee arthroplasty (TKA) at a 10 years' follow-up. Beyond this time frame, the risk of polyethylene wear related to the technical restrictions of the UKA is another consideration. Indeed, to prevent the risk of rapid extension of osteoarthritis to the opposite compartment, the procedure should be limited to restoring the patient's constitutional axis before wear phenomena had set in. This makes UKA a surgical procedure at risk of failure due to wear phenomena. Much of this paper will describe the precise rules for UKA positioning, which are critical to observe to warrant these implants outcome and longevity.

Total knee replacement in post-traumatic arthritic knees with limitation of flexion.

UNLABELLED: The objective of this study is to investigate the results of total knee arthroplasty (TKA) in traumatic osteoarthritis cases with flexion restriction and to describe the technical details of their management. A multicentre series comprising 40 patients with limitation of flexion less than or equal to 90° was selected from 152 cases of post-traumatic knee arthritis with malunion. We hypothesized that the arthroplasty complication rate would be higher than in other etiologies of limitation of flexion and would require specific management strategies. PATIENTS: In 23 cases, intra-articular malunion was present, in 15 cases extra-articular, and in two cases combined. The mean flexion was 72±23°, extension was 6±6°, and total range of motion (ROM) 66±23°. Eight cases of flexion restriction were severe (flexion<50°), six intermediate (flexion, 50-70°) and 26 moderate. In 14 cases, the anterior tibial tuberosity was osteotomized (43% intra-articular malunion and 6% extra-articular malunion). Five simultaneous realignment osteotomies were necessary. In severe cases of limitation of flexion, five extensive quadriceps releases were associated. RESULTS: Four mobilizations under general anesthesia were performed. In the cases of severe limitation of flexion, we noted three avulsions of the patellar tendon, two cases of cutaneous necrosis, one of which was associated with deep infection, and another case of deep infection. In the cases of moderate limitation of flexion, we noted one case of nonunion of the tibial tuberosity and two cases were revised for loosening, one aseptic and the other septic. With a mean follow-up of 5±4 years, the mean flexion was 99.4°±23 for a gain of 26.7±20°. The final flexion and the gain in flexion were correlated with preoperative flexion (r=0.62 and r=-0.47, respectively). The final amplitude was 99±27° for a gain of 33±21°. The flexion gains were comparable for both types of malunion, whether they were intra- or extra-articular. DISCUSSION: Arthroplasty provided a substantial gain in flexion. Osteotomy of the tibial tuberosity and the realignment osteotomies should be performed if necessary, with no risk of compromising the result. Superior gains can be sought in severe cases of limitation of flexion by releasing the extensor apparatus, in absence of cutaneous scar tissue retractions and recent infection. LEVEL OF EVIDENCE: Level 4. Noncomparative retrospective study.

Post-traumatic knee osteoarthritis treated by osteotomy only.

BACKGROUND: Osteotomies to address lower extremity post-traumatic deformities are more complex than standard osteotomies performed for congenital deformities, standard osteotomies and their outcomes are not well known. We performed a multicentric retrospective study of these cases. We hypothesized that osteotomy without total knee replacement to correct fracture malunion deformities can provide long-term relief from athritic pain. PATIENTS AND METHODS: Twenty-eight patients, mean age 46.4 years old, underwent, between 2000 and 2008, osteotomy for post traumatic osteoarthritis which had resulted in intraarticular malunion in six patients and extraarticular malunion in 22 cases. The initial trauma had occurred a mean 17.3 years before. There were 11 valgus and 17 varus deformities. Two osteotomies were performed in the callus to correct intraarticular malunion. The other osteotomies were performed outside the callus: in 25 cases to correct coronal plane deformities (nine tibial, 11 femoral and five tibial and femoral), including nine cases with associated derotation. Osteotomies were performed on the distal femoral metaphysis and the proximal tibia. There was also one case of supramalleolar derotation osteotomy of the tibia. All 28 patients were contacted again for a consultation. There was a postoperative clinical and radiographic follow-up of at least 2years for all patients despite four lost to follow-up patients. There were 18 patients with Ahlback grade 2 arthritis, nine grade 3 and one grade 4. RESULTS: Two patients with an intraarticular malunion finally underwent revision surgery to receive total knee replacement because of persistent pain. These patients had grade 3 and 4 arthritis respectively and undercorrection persisted in the coronal plane. Four patients underwent repeated surgery for stiffness, early infection treated with debridement and antibiotics as well as femoral pseudarthrosis (two cases). After a mean follow-up of 3.8 years, the pain score had improved significantly with more marked improvement in extraarticular malunions (P=0.03). Functional improvement was moderate (equivalent in patients with Ahlback grades 2 and 3 arthritis) and articular range of motion did not change. Osteotomy corrected valgus and varus deformities with a mean realignment effect of 9° and 10° respectively. DISCUSSION: Osteotomy should correct the three components of the traumatic deformity at the distal femoral metaphysic level to allow mechanical axis and rotation anomalies correction, and at the proximal tibia level for realignment purposes. Supramalleolar tibial osteotomy should be performed for tibial derotation. Pain relief with osteotomy had better outcomes when dealing with extraarticular malunions. In unicompartmental grade 2 and 3 arthritis, the indications can be fairly broad in young patients. Besides providing temporary relief, osteotomy facilitates future total knee replacement surgery in these cases. LEVEL OF EVIDENCE: Level 4; non controlled, retrospective study.

Total knee arthroplasty for osteoarthritis secondary to extra-articular malunions.

INTRODUCTION: Post-traumatic total knee arthroplasty for extra-articular malunion requires correction of the deformity, either through asymmetrical bone resection (possibly inducing ligaments imbalance) or osteotomy at the time of arthroplasty. We report the results of a continuous multicenter, retrospective series of 78 patients (18 implants with osteotomy) with a mean 4 years of follow-up. The hypothesis is that the selected procedure requires to be based on the deformity's location and severity. PATIENTS: With a mean age of 63 years (younger in the osteotomy group), 38 patients had femoral malunion, 36 had tibial malunion, and four had a combined malunion. There were 70 frontal deformities (48 varus and 22 valgus) and 10 rotational deformities, often diaphyseal, four of which more than 20°. Twelve patients had a history of infection; eight had frontal laxity greater than 10°, and 15 a limited range of motion in flexion. In 70 cases, semi- or nonconstrained implants were used, and in eight cases more constrained implants, including four hinge prostheses. RESULTS: We observed two deep infections, one case of avulsion of the extensor mechanism, and two cases of aseptic loosening with femoral malunion and varus deformity. Two osteotomies resulted in nonunion, one with internal fixation devices mobilization requiring revision using extension rods. The function and pain scores were significantly improved. The mobility improvements were moderate but did not compromise the surgical procedure main objective. The preoperative hip-knee angle was corrected with both techniques. Only the function score gain was greater for the isolated arthroplasty procedures. DISCUSSION AND CONCLUSION: The indications for arthroplasty alone were extended to 20° varus and 15° valgus, with no major residual laxity. Beyond 10°, hinge prosthesis should be available. Associated osteotomy can correct rotational deformities that cannot be compensated with bone cuts. In deformities that are close to the joint, osteotomy facilitates implantation of moderately constrained prosthesis. This indication is based on CAT scan rotational deformities measurements because rotational deformities require an osteotomy, and/or the presence of extraligamentous deformity that cannot be reduced with collateral ligaments surgical release. LEVEL OF EVIDENCE: Level 4. Non-controlled retrospective study.

[Neurogenic osteoarthropathy of the knee associated with spina bifida: a diagnosis not to be missed]. / Ostéoarthropathie neurogène du genou associée à un spina bifida : un diagnostic à ne pas méconnaître.

Neurogenic arthropathy is a severe complication of chronic sensitive deficits that occurred commonly in diabetic neuropathies. It is a destructive and painless osteoarthritis associated with a loss of the deep sensitivity and a defect of protective reactions against chronic articular microtraumatisms. We report a 55-year-old woman with neuroarthropathy of the knee resulting from a spina bifida. Bisphosphonate use is an effective but non-consensual treatment.

Alignment influences wear in the knee after medial unicompartmental arthroplasty.

Failure of a medial unicompartmental arthroplasty may be related to wear of the cartilage in the opposite compartment or to wear in the polyethylene tibial implant. Limb alignment influences both of these factors in the long term. Fifty-eight knees with medial unicompartmental arthroplasties in patients alive at least 10 years postoperatively were evaluated for radiographic changes at their most recent followup. The average duration of clinical and radiographic followups for these patients was 15 years (range, 10-20 years). Alignment was measured preoperatively and postoperatively as the hip-knee-ankle angle on radiographs of the entire limb. An overcorrection in valgus of the preoperative deformity (hip-knee-ankle angle > 180 degrees was associated with an increased risk of degenerative changes in the opposite compartment. Severe undercorrection in varus of the deformity (hip-knee-ankle angle < 170 degrees) was associated with increased wear in the tibial component and recurrence of the deformity which was indicative of polyethylene wear. For medial implants that were implanted in moderate varus (hip-knee-ankle angle of 171 degrees to 179 degrees) the rate of wear of the polyethylene was less than in knees with severe undercorrection and the risk of degenerative changes in the opposite compartment was low.

[Revision total knee arthroplasty after unicompartmental femorotibial prosthesis: 54 cases]. / Reprise de prothèse unicompartimentale fémorotibiale par prothèse totale du genou. Résultats d'une série de 54 cas.

PURPOSE OF THE STUDY: We analyzed technical difficulties encountered when performing revision total knee arthroplasty in patients with unicompartmental femorotibial prostheses. MATERIAL AND METHODS: This multicentric retrospective study included 54 revisions of unicompartmental femorotibial prosthesis with implantation of a total knee prosthesis. The series included 45 medial and nine lateral compartment prostheses. A gliding total knee prosthesis was implanted in 53 cases (98%) (39 standard, 14 revision). Mean time to failure of the unicompartmental prosthesis was four years. IKS scores were established at review. The radiological work-up included AP and lateral views in single leg stance and goniometry for 22 medial compartment revisions. Twenty-seven patients were seen for physical examination and x-rays and eight were lost to follow-up; data were recorded from medical files for 19 patients. RESULTS: The revision procedure was considered easy in 82% of the cases. Mean follow-up after revision was four years (range 2 - 12 years). Subjective outcome was very satisfactory for 56% of the patients, satisfactory for 36% and unsatisfactory for 8%. The mean function score was 62 points, the mean knee score 85 points, and the mean flexion was 113 degrees. No laxity was found for 90% of the knees. The femorotibial angle was 180 +/- 2 degrees in 46% of the patients. The mechanical femoral angle was 90 degrees in 54% of the patients with 2-4 degrees varus in 42%. The mechanical tibial angle was 90 degrees in 46% of the patients with 2-8 degrees valgus in 37%. Complications included pulmonary embolism (n=2), mobilization under general anesthesia (n=3), arthrolysis (n=1), lateral vertical patellectomy (n=1), and secondary infection (n=1). There were five failures requiring changing the total knee prosthesis. DISCUSSION: Loss of bone stock raises specific problems during revision of unicompartmental knee prostheses. Loss of tibial bone is more frequent but it is more difficult to correct for loss of femoral bone. A gliding knee prosthesis is generally preferred for first intention revision. We recommend a long stem when the bone defect is important or involves loss of cortical bone. We have had good mid-term results with revision total knee prostheses after unicompartmental prostheses. Longer follow-up is needed. Poor results were obtained when revision was performed for persistent pain without a clearly defined cause. The presence or not of significant bone loss did not appear to affect outcome. The observation of medial laxity in case of failed lateral unicompartmental prostheses suggests a more constrained total knee prosthesis might be indicated. Compared with earlier series, our results with total knee prostheses after unicompartmental prostheses appear to be better than after tibial valgus osteotomy and also better than after total knee arthroplasty. Conversely, they would be less satisfactory than for primary total knee arthroplasty. The surgical procedure for revision total knee arthroplasty after unicompartmental prosthesis requires precision and skill but is not technically difficult.

Patellar impingement following unicompartmental arthroplasty.

BACKGROUND: Patellofemoral complications (osteoarthritis and impingement) have been rarely reported after unicompartmental arthroplasty, and their long-term consequences are not known. The purpose of the present study was to analyze these complications following unicondylar arthroplasty. METHODS: We evaluated the results of ninety-nine unicompartmental arthroplasties that had been performed in eighty patients with osteoarthritis of the knee. The medial compartment was replaced in seventy-four knees and the lateral compartment, in twenty-five. All ninety-nine knees were evaluated with regard to patellar impingement and osteoarthritic changes on skyline radiographs after an average duration of follow-up of fourteen years (range, ten to twenty years). In addition, the seventy-seven knees (fifty-eight patients) that had not been revised were evaluated with use of the clinical scoring system of the Knee Society and specific questions regarding patellofemoral symptoms after an average duration of follow-up of fifteen years (range, ten to twenty years). The relationship between patellar complications (osteoarthritis and impingement) and the position of the femoral component was evaluated with use of lateral radiographs of the knee. RESULTS: At the time of the most recent follow-up, twenty-nine knees had osteoarthritic changes in the portion of the patellofemoral joint opposite the compartment with the implant and twenty-eight knees had impingement of the femoral component on the patella. The knees that had impingement did not have osteoarthritic changes. Pain while ascending or descending stairs and pain on rising from a chair were noted more frequently in knees with patellar complications (impingement and osteoarthritis) (p = 0.02), and these symptoms affected the stair-climbing functional score. These symptoms were more severe in knees with patellar impingement than in knees with degenerative changes. One revision was performed because of patellar impingement. Patellar impingement was more frequent after lateral arthroplasty than after medial arthroplasty (p = 0.02) and was associated with placement of the femoral component too far anteriorly (p = 0.001). CONCLUSION: After unicompartmental arthroplasty, the patellofemoral joint was affected by degenerative changes and patellar impingement. These complications appeared to have been mutually exclusive and affected the functional outcome of the arthroplasty. Patellar impingement affected the knee more severely with regard to both symptoms and the need for revision.

Metabolic engineering of Escherichia coli: construction and characterization of a gltA (citrate synthase) knockout mutant.

E. coli is one of the most important host organisms for recombinant protein production. However, growth and recombinant protein production can be limited by acetate accumulation during high-cell-density fermentations. Some of the strategies used to overcome this problem are based on the alteration of the genotype of the host. This paper discusses the construction and characterization of an E. coli gltA- knockout mutant. The knockout of the gene was confirmed by the loss of citrate synthase activity in an enzyme assay. Also the growth rate of the mutant on Luria Broth and Luria Broth + acetate was reduced.

[Revision in non-infected total knee arthroplasty: an analysis of 69 consecutive cases]. / Les changements de prothèses totales du genou non infectées. Analyse des résultats d'une série continue de 69 cas.

PURPOSE OF THE STUDY: We reviewed 69 consecutive cases of total knee arthroplasty revisions to analyze the causes of failure. MATERIAL AND METHODS: Sixty-nine total knee arthroplasty revisions were required between 1990 and 1997 for non-septic failure. Five categories of failures were identified: 30 loosenings including 11 with an initial malposition (varus position of the tibial component in 8 cases), 14 laxities (medial in 5, lateral in 5 and anteroposterior in 4), 11 stiff knees with no other clinical or radiological anomaly, 6 patellar failures (2 dislocations, 2 cases of excessive wear, 2 painful knees with a Freeman prosthesis), and 8 cases of painful knees with no other detectable anomaly. RESULTS: A three-phase reconstruction procedure was used after removing the failing TKA: 1) reconstruction of the tibia with replacement of lost bone, 2) reconstruction of the femur with balanced flexion determining the size of the implant, 3) balanced extension determining the distal/proximal position of the femoral component. A "simple" sliding prosthesis was used in 16 cases, a modular reconstruction prosthesis in 40 cases and a hinge prosthesis in 13 cases. Mean follow-up for functional and radiographic assessment after revision surgery was 37 months (59 cases) with a minimum follow-up of 1 year. The best outcome was observed in the "loosening", "laxity", and "stiffness" patients. Outcome was less favorable for the group "isolated pain" with IKS functional scores of 35.5 +/- 16 and 52.5 +/- 21. DISCUSSION: In 36 p. 100 of cases, TKA failure was related to a technical mistake (component malposition, poor ligament alignment). In 33 p. 100, failure was patient related (multiple procedures, congenital hip dysplasia, rheumatoid arthritis.). Outcome after revision TKA was less favorable than after primary TKA, particularly in case of painful knees with no other detectable anomaly. CONCLUSION: Surgical revision of TKA must follow a rigorous procedure with a detailed preoperative work-up. The decision for revision must not be made unless a precise anomaly has been identified.

Laxity in posterior cruciate sparing and posterior stabilized total knee prostheses.

Two series of consecutive total knee replacements were compared retrospectively: 118 HLS II posterior stabilized prostheses (Group 1) versus 138 HLS CP posterior cruciate ligament sparing prostheses (Group 2). Both implants were made by the same manufacturer. The prostheses had been inserted between 1989 and 1992. Mean followup was 4 years. The authors looked for evidence of laxity in the coronal and the sagittal planes, the correlation of laxity with other factors, and the effect of laxity on the objective and subjective outcome as measured with the Knee Society score. Group 2 had significantly more clinical and radiologic laxity. There was little difference between the two groups regarding the overall objective and subjective outcome; however, there was a significantly higher rate of excellent results in Group 1. Longer followup will be required to see whether the implants with laxity are at heightened risk for tibial component wear.

[Total knee replacement after valgus tibial osteotomy. Technical problems]. / Prothèse totale du genou après ostéotomie tibiale de valgisation. Problèmes techniques.

Forty total knee replacements following valgus tibial osteotomy were analysed. There were 38 patients (10 men and 28 women) with a mean age of 72 years at the time of the joint replacement, at a mean of 8.5 years after osteotomy. Mean follow-up was 3 years (1 to 5 years). Performing a total knee replacement after valgus tibial osteotomy posed some specific problems due to asymmetrical bone cuts, residual ligament laxity, loss of bone at the tibial plateau, and especially when there was a malunion of the previous osteotomy. The functional results were good. A group of 208 patients with total knee replacements for untreated osteoarthritis acted as a control for comparison. In the group with an osteotomy the results were worse in respect of the walking distance and flexion angle achieved after joint replacement compared with primary replacement (p < 0.001). However the GUEPAR and HSS score 77.2 +/- 2.3 were very similar. Using unilateral weight-bearing X-rays, 18.8p. 100 demonstrated opening from ligament laxity and 40.6p. 100 had radiolucent lines under the components, which was the same as in the control group. The tibio-femoral mechanical axis using long-leg films had a mean varus angle of 0.7 degrees.

Intracranial bullet migration--a sign of brain abscess: case report.

An unusual case of migration of an intracranial bullet fragment within a brain abscess is reported. Movement of the bullet was first detected on skull films, and the significance of this finding on plain radiographs is emphasized.