Objectives

The appropriate treatment for chronically infected TKR is controversial. One-stage exchange is believed to be possible only in selected cases, but the respective indications and contra-indications and the criteria of selection are not fully validated. We wanted to test the relevance of the commonly used selection criteria by comparing two groups of patients: the control group operated on with a routine one-stage exchange without selection criteria, and the study group operated on by one stage exchange on selected patients only. We hypothesized that selected one-stage exchange gives fewer failures than routine one-stage exchange procedure.

Introduction: diaphyseal bone defect is one of the most difficult challenge in Orthopaedic and Traumatologic Surgery. One of the techniques for reconstruction of bone defect described by Masquelet is a two-stage procedure: induction of a membrane around a ciment spacer and autologous cancellous bone graft with external fixator. The aim of the study is to evaluate a modified technique with intramedullary nailing for tibial bone defect.

Materials and Methods: between 2001 and 2006, 13 patients presented important tibial bone defect. On radiological examination, the mean size was 18,5 cm³ (12–30 cm³). Initially, there were 12 opened fractures (1 Gustilo 1, 2 Gustilo II, 9 fractures Gustilo III), and one osteomyelitis following a compartment syndrome. The mean age of the patients at the procedure was 41 years old (18–74). Our modified technique was as follows:

several debridment and stabilization of bone fragments with a temporary external fixator

10 patients had hyperbare oxygenotherapy. All patients were evaluated radiographically and by physical examination. using SF-36 questionnary.

Results: There was no amputation but 4 complications. There were 3 deep infections: one just between the 2 stages and one 2 years after the second stage: both were treated by nail exchange and adapted intra-venous anti-biotherapy. The third one was the complete bone graft resorption because of an infection just after the second stage (the only failure of the method). The fourth complication is the nonunion 13 months after the second stage: nails has broken and has been changed. Bone healing was obtained in 12 patients at mean follow-up was 32 months (12–69). They were able to walk 4,3 months after bone grafting. 8 patients answered to the SF-36 questionnary: overall function was limited with a mean score of 99.8.

Discussion: and conclusion: Our modified technique gave satisfactory results at medium term. Nailing, comparing to external fixator, offers a better stabilization of bone fragments, better control of axis and length of lower limb, and an easier access for plastic surgery and nurse care. Others bone reconstruction treatment like ilizarov bone transport, free vascularized fibula fiap or allograft are still possible if failure. However, the rate of deep infections are quite high (4/13) may be questionable. Sacrifice of intramedullary blood supply and the difficulties to confirm union on radiological exams are still problematics.

Intraoperative assessment of knee kinematics should help surgeons optimizing total knee replacement. The purpose of this work was to validate information delivered by an adapted navigation system in 10 healthy cadaver knees and to investigate kinematics of 10 osteoarthritic (OA) knees in patients undergoing total knee replacement. The system displayed the magnitude of axial rotation, the position of the instantaneous centre of axial rotation and the displacements of the condyles. Successive cycles from full extension to 140° of fiexion in the same knee produced a mean external rotation of 19.7±10°, which was correlated to knee fiexion (r=0,60±0.2 in healthy knees, r=0.79±0.14 in OA knees). The center of axial rotation migrated posteriorly an average of 8.2 mm in both groups. The posterior displacements were 4.0 ±5.4 mm in healthy and 5±6.3 mm in OA knees for the medial condyle, and 20.9±9.1 mm in healthy and 20.3±10 mm in OA knees for the lateral condyle. The medial condyle lifted off beyond 110° of fiexion. Results in healthy knees were consistent with those obtained using fiuoroscopy and dynamic MRI. The kinematics of healthy and of OA knees with an intact anterior cruciate ligament did not differ significantly.

Introduction: Fifteen revision knee arthroplasties were navigated (Praxim, Grenoble, France). The purpose was to investigate whether revision procedures would require a dedicated navigation system.

Material: Two prostheses were revised for severe instability, two for catastrophic failure due to poly wear, 9 for loosening (1 femoral, 1 tibial and 3 both components in total knee arthroplasties, 3 femoral and 1 tibial in uni), two for late infection in extensively cemented prosthesis. The patients were revised using TC3 postero-stabilised revision implants (Depuy, Warsaw, Indiana) and one with hinge prosthesis.

Method: Preoperatively, the rotation of the femoral component was investigated by scanner, and the ideal level of the joint line was determined relative to the fibula head on the healthy contralateral side.

Navigation was performed with dependant bone cuts, tibia first. The tibial trackers were implanted distally, while the femoral trackers were implanted medially close to the joint line, to prevent impingement with the stems.

Bone morphing was performed on the surface of the ancient prosthesis. The system showed the difference between the level of the ideal joint line and the real bone cut, thus indicating the height that had to be reconstructed. The provisional tibial plateau was assembled with its stem and its metallic augments and the knee was balanced with the new tibial component and the ancient femoral component still in place. Femoral reconstruction was finally performed based on an ideal position that had memorized by the computer

Bone reconstruction was required in 2 tibias (morselized allografts) and in one femur (structural femoral head allografts).

Results: With a 6-months minimum follow-up, there was no postoperative complication. The HKA angles ranged from 176 to 185. The patella appeared centered on the Merchant view in 14 cases. The femoral rotation was contained between 0 and 5 degrees of external rotation. The 6 month ranges of flexion were 105° with an average gain of −4°.

Conclusion: The navigation was a precious help to guide reconstruction of both extremities tibial and femoral, while maintaining the level of the joint line. The navigation system designed for primary surgery appeared convenient to perform revision surgery.

Objective: To evaluate the clinical and radiological outcome of an intra-articular bone-patellar tendon-bone (B-PT-B) anterior cruciate ligament reconstruction in combination with an extra-articular tenodesis (Lemaire procedure), at very long term follow-up.

Methods: Out of a total of 148 patients, 100 were available for clinical and/or radiological evaluation in 2006. The minimum follow-up is 21 years with a mean of 24.5 years. Outcome parameters included objective (IKDC) and subjective (KOOS) clinical scores, and radiographs (standing, TELOS).

Results: 84% of the patients were very satisfied or satisfied. The objective IKDC classification was: A=17%, B=41%, C=34%, D=8%. In 2006, 27% had narrowing < 50% (C) and 27% had narrowing > 50% (D). Onset of osteoarthritis correlated with medial meniscus status and medial femoral chondral defects. Knees with a preserved (healthy or sutured) medial meniscus had a significantly (p< 0.05) better radiological outcome. 24% had narrowing < 50% (C) and 12% had narrowing > 50% (D). Risk factors for osteoarthritis were: medial meniscectomy, residual laxity, age at intervention and femoral chondral defects.

Conclusion: The outcome of anterior cruciate ligament reconstruction using a B-PT-B in combination with extra-articular tenodesis is satisfactory in the very long term, in knees with a preserved medial meniscus and normal cartilage.

Introduction. The treatment of complex fractures of the proximal humerus still raises controversy, particularly in those 3 or 4 part fragments fractures, which are at risk for osteosynthesis (poor fixation in poor bone) or for secondary avascular necrosis. Conventional hemi-arthroplasty has currently remained the most common surgical treatment, but the recovery of active mobility remains incomplete and disappointing.

Inverted shoulder arthroplasty has been initially proposed for the treatment of omarthrosis secondary to deficient rotatory cuffs, however its use in acute traumatology has not been yet investigated.

Material and Medthod. We hereby present the results obtained in 43 consecutive patients (41 women and 2 men) which were retrospectively reviewed with a mean follow-up of 21 months (5–58). The mean age was 78 years-old (64–97). There were 5 three-part fractures, 26 four-part fractures and 12 four-part fracture dislocations. All patients were clinically and radiologically assessed, except two, who deceased with incomplete follow-up data.

Results. The clinical outcome was satisfactory with a mean active forward elevation of 97° and a mean active external rotation in abduction (ER 2) of 30°. The mean Constant score was 44 points (16–69). The mean ponderate score was 66% (25–97%). The mean pain score was 12.5/15, the mean activity score was 10.9/20, the mobility score was 17.6/40 and the strength score was 3.6/25. The mean ponderate score of the controlateral shoulder was 105 %(80–130).

The mean ASES score was 9 points (0–19) out of 24. The mean DASH score was 44 points (0–92) out of 100.

Post-operative complications included 3 reflex sympathetic dystrophies, 5 regressive neurological complications, 1 loosening of the deltoid suture, 1 anterior dislocation and 1 acromion fracture. There was no infection.

Radiographs at last follow-up showed peri-prosthetic calcifications in 36 cases, displacements of the tuberosities in 19 cases and scapular notches in 10 cases (1 type III, 3 type II and 6 type I notches). No migration of the prosthetic components was observed.

Discussion. Satisfactory mobility scores can be obtained in the treatment of complex shoulder fractures in the elderly, despite frequent deficiencies of the rotator cuff, whatever their causes, degenerative or traumatic (secondary displacement).

Conclusion. Inverted shoulder arthroplasty might constitute an interesting alternative in the treatment of displaced 3 or 4 part fragment fractures in the elderly over 70. Long term results are required before extending the indications to younger patients or to other types of fracture.

Introduction. Using conventional tests, manual computer-assisted methods offer a satisfactory reproducibility and accuracy in wear evaluation in knee arthroplasty. However, repeatability may be underestimated. Various calibration methods were proposed but not tested. Accuracy may decrease with fluoroscopic images.

Method. We recalculated intra- and interobserver variability based on 132 fluoroscopic images of 3 unimplanted specimens, using specific analyses like the Brand and Altman test or the repeatability coefficient. Calibration was tested in comparison to a reference method (based on a circular shape of known diameter). The influence of a radiological marker embedded into the central part of the polyethylene to control the incidence of fluoroscopic guided images was tested. Accuracy was compared between fluoroscopic and digitized plain radiographs.

Results. The coefficient of repeatability indicated a variation of 0.4 mm in repeated measurements by the same observer. Although a high interobserver reproducibility (r=0.99), the Brand-Altman test showed inconsistent values in about 30% of cases with both observers. The method of calibration influenced the results significantly. Under ideal conditions of radiographic incidence, the accuracy was better with a digitized x-ray (0.10 mm) than with fluoroscopic images (0.25 mm), and compared favourably with fully automatized methods. If small variations of radiographic incidence occured, the accuracy droped to 1 mm. A comparison of successive radiographs of the same implant showed that 1° tilting induced an average reduction of 0.36 mm in the apparent thickness of the polyethylene.

Discussion. When comparing wear measurements in TKA using manual, computer-assisted methods, examination by a single observer should be preferred. The difference between the measurements of the thickness of the polyethylene insert on two images taken with exactly the same incidence should be considered significant if it is greater than twice the precision of the method, i.e. greater than 0.20 mm on digitized X-ray images, or greater than 0.50 mm on fluoroscopic images. In the absence of a strict control of the radiographic incidence, it appears that the difference between the measurements of the thickness of the polyethylene on two images should be considered significant only if it is greater than 2 mm. Given the estimated wear rate of conventional TKR, 10 years of use of the prosthesis would be needed before such systems can detect wear with certainty.

Conclusion. A metallic marker of known dimension embedded in the central part of the polyethylene insert appears mandatory to control calibration as well as the angle of incidence of fluoroscopically guided radiographs. This would improve the performance of radiographic measurements enough to offer clinical relevance.

MATERIAL AND METHODS. From 1986 to 2002, among 195 fractures treated with this plate, 181 were evaluated. A first series of 116 cases analysed in 1997 (follow up 22 months) was enlarged by a recent series of 65 cases (follow up 29 months). According to Duparc, there were 5(2.7%) type II, 69(36.9%) type III, 103(55.1%) type IV, 10(5.3%) type V. According to Sanders there were 67(37%) type 2, 65(36.9%) type 3, 49(27.1%) type 4. The protocol was as follows: fractures were investigated with standard views (including Broden’s views) and CT scans. The average delay before surgery was 5.5 days. Blisters were not a contraindication to surgery, if not obviously infected.

Reduction was performed by an extended lateral approach, and checked under fluoroscopy. Joint reduction was fixed by screws. The reconstruction plate, bent in a standard way, was then placed laterally, from above the tuberosity towards the inferolateral part of the anterior process. All but one or two posterior screws ideally converge to the sustentaculum tali (ST), building a strong support below the posterior facet. Postoperatively partial weight bearing below the threshold of pain was allowed in the majority of cases. Clinical results were assessed using the French Orthopaedic Society (SOFCOT) functional score for both series, and AOFAS (American Foot and Ankle Society) score, and Mary-land Foot Score (MFS) for the recent series.

RESULTS. According to the SOFCOT, there were 74% good and excellent results. The average MFS was 87/100, the average AOFAS score, 82/100. The average beginning of walking without crutches was 10 weeks. In the second series of 65 cases, 78.4% of active patients went back to their previous job at the same level.

Reduction was assessed anatomic on the postoperative Broden view in 90.5% of cases. The average Böhler’s angle remained stable. Secondary fusion of the subtalar joint was required only in 4 cases (2.1%). Wound healing was delayed in 19.7%, but generally, it was spontaneously obtained in a few weeks. Three deep late infections (1.6%) healed after plate removal.

DISCUSSION. ORIF of displaced articular calcaneal fractures using a contoured lateral plate has yet become a routine in our institution. The concept of screws converging from the plate to the ST, which is the strongest part of the broken bone, provides both optimal fixation of the primary fracture line (separation fracture), and a solid support below the reduced posterior facet. In most of cases early partial weight bearing did not jeopardize articular reduction, except the 4 (2.2%) significant secondary displacements. Therefore, in very comminuted fractures involving the tuberosity, we rather use of the new AO locked Plate.

Conclusion: Because the reconstruction plate was always modelled in the same standardized shape, we developed a specific precontoured thinner plate.

Purpose of the study: The accuracy, reproducibility and concordance of wear measurements made with the Imagika system were tested on knee prostheses.

Material and methods: Anteroposterior radiographic images of implants with tibial inserts measuring 9, 7, and 11 mm thick were obtained, the tibial base had a 28 mm bead for calibration. The ap images were digitalized and variations in incidence were controlled with a plumb line. Combining the tilt positions from −10° to +10° and rotation from −5° to +5°, a total of 132 images were obtained. Four groups were defined according to tilt and rotation (±5°, ±3°). The images were read by to observers. Reproducibility and agreement were assessed for the overall series and for each of the four groups. Two images were read 40 times by the same observer using variable digital quality (100–300dpi) to determine measurement accuracy and error. Results were compared with the manufacturer’s data sheet.

Results: Measurement agreement was poor in the four groups. Reproducibility was excellent at the 1% threshold for the overall series and for groups 3 and 4 for both observers. The accuracy improved from 0.6 to 0.5 mm by improving digitalization from 100 to 300 dpi with an error to the order of 0.05. Guiding the points used by the software for measurements, the accuracy could be improved to 0.25mm. The difference between the lateral plateau and the medial plateau appeared for the lesser tilt and for rotation greater than 2°. The thickness displayed was close only for the groups with little tilt.

Discussion: The reproducibility and accuracy of the Imagika system can be brought below the 0.5 mm threshold. For views without tilt, the difference compared with the displayed values varied from 0.1 to 0.3mm. The agreement remains poor if the position of the measurement points is not predefined by the system.

Conclusion: Offering an excellent reproducibility and good accuracy, the Imagika system enables monitoring TKA wear if the incidence of the radiographic images is perfectly controlled. For a more quantitative approach, the calibration method would have to be improved.

Purpose of the study: The aim of this study was to investigate the influence of bone cuts on the degree of postoperative flexion for total knee arthroplassty in patients with a potential for good postoperative recovery of flexion.

Material and methods: Adobe Photoshop and Imagika were used to process lateral radiographs of a normal knee and simulate implantation of total knee prostheses using phantom images of femoral components of decreasing size as well as variations in the tibial slope (HLS system, Tornier). The femoral and tibial images were moved until the maximal flexion angle or impingement between the posterior tibial border and the femoral cortical occurred. The same types of implantations were simulated with real implants on cadaveric bones using the Ci navigation system (Depuy) to check the position of the bone pieces and the bone cuts. The different implantations simulated involved four femoral pieces of decreasing size with a constant tibial slope. Then the same femoral implant was used varying the tibial slope by 5° increments from -5° to +10°. Rollback during flexion could be regulated by the software by controlling the position of contact of the condyle son the corresponding tibial plateau.

Results: With the two methods, reducing the posterior condylar rim 3 mm decreased the flexion angle by 10°, modifying the tibial slope 5° induced a 5° variation in the flexion angle at impingement. A 10mm posterior rollback improved the flexion angle 10° and inversely. Cumulatively, these modifications can lead to a loss of 30° flexion.

Discussion: When regulating the space in flexion, it is sometime necessary to modify the tibial slope or the posterior condylar rim by increasing the posterior condylar cut. Depending on the prosthetic kinetics, this may modify the flexion angle intraoperatively, especially if these changes are combined, decrease in the tibial slope often being associated with an increase in the posterior condylar cut.

Conclusion: The technique used for the bone cuts for a total knee arthroplasty can potentially have a significant effect on the maximal angle of maximum flexion achieved by the patient.

Purpose of the study: Locked plating is an attractive alternative to external fixation for the fixation of distal shaft fractures of the radius, particularly in cases with metaphyseal comminution. The purpose of this study was to assess prospectively outcome with locked anterior plate fixation in a series of 43 complex fractures of the distal radius treated between October 2003 and November 2004.

Material and methods: The AO LCP 3.5 plate (Synthes) was used. The series included 27 women and 15 men, mean age 55.5 years (range 17–83 years). We included fractures with major metaphyseal comminution according to the M.E.C classification established by Laulan (18 M2, 14 M3, and 9 M4). According to the AO classification, there were nine extra-articular fractures (eight A3 and one A2) and 35 articular fractures (ten B3, two C1, four C2, and seventeen C3). Posterior displacement was noted for 22 fractures. In eight cases plate fixation was a second intention procedure due to secondary displacement occurring on average eight days (range 3–21 days) after trauma for a fracture initially treated with infrafocal pinning. An epiphyseal locking screw was used in all cases. An antebrachiopalmar immobilization orthesis was worn for six weeks on average (range 3–9 weeks). The first-intention anterior plating was combined with an intrafocal posterior pin for 13 patients and with an external fixator in one. Radiographic outcome was reported in terms of joint congruency and using the SOFCOT symposium criteria for the 41 patients reviewed at bone healing.

Results: Anatomic restitution was achieved in 23 patients (55%). There were two purely intra-articular calluses due to failure of the primary reduction, both measured less than 2 mm. Fifteen moderate misalignements (36%) were noted, most (84.7%) involving moderate sagittal inclination, the distal radioulnar index being preserved. Two major misalignments (5%) were related to early disassembly of the osteosynthesis.

Conclusion: Locked anterior plating has provided promising results for maintaining radial length in distal radial fractures with major metaphyseal comminution. There remains a certain number of cases with a moderate and persistent posterior inclination and a few cases of defective intra-articular reduction.

We used an inverted shoulder arthroplasty in 43 consecutive patients with a mean age of 78 years (65 to 97) who had sustained a three- or four-part fracture of the upper humerus. All except two were reviewed with a mean follow-up of 22 months (6 to 58).

The clinical outcome was satisfactory with a mean active anterior elevation of 97° (35° to 160°) and a mean active external rotation in abduction of 30° (0° to 80°). The mean Constant and the mean modified Constant scores were respectively 44 (16 to 69) and 66% (25% to 97%). Complications included three patients with reflex sympathetic dystrophy, five with neurological complications, most of which resolved, and one with an anterior dislocation. Radiography showed peri-prosthetic calcification in 36 patients (90%), displacement of the tuberosities in 19 (53%) and a scapular notch in ten (25%). Compared with conventional hemiarthroplasty, satisfactory mobility was obtained despite frequent migration of the tuberosities. However, long-term results are required before reverse shoulder arthroplasty can be recommended as a routine procedure in complex fractures of the upper humerus in the elderly.

Aim: The operative management of proximal humerus fractures is still viewed as an unsolved question.

Surgical treatment aims at restoring anatomical elements to a condition stable enough, to allow early mobilization to avoid secondary displacement. The blood supply of the humeral head should not be damaged, so the risk of avascular necrosis will be minimal.

This work offers a new surgical technique that dramatically reduces the need for dissection of soft tissues while using a new locked plate.

Material and Method: This prospective study was carried out between August 2002 and March 2004. 47 fractures of the humerus proximal were operated on 47 patients aged 63 as an average. There were 9 four part fractures, 18 three part and 17 two part fractures.

The two arms of this Y shaped plate embrace the humeral head. The anterior arm overbridges the biceps longus tendon and fixes the lesser tuberosity, with a locked screw in the head. The posterior arm fixes the greater tuberosity with an another locked screw. These two screws cross each other at nearly right angle thus giving optimal fixation in the head.

Results: Fourty four patients (44 shoulders) were later re-examined with 10,3 months mean delay. Re-education was made immediate for 85% of the cases. The final evaluation was made with the functional Constant score and X ray control.

The main complications were 3 algodystrophies, 1 hematoma, 4 failures of fixation, 2 nonunions and only one necrosis.

Conclusion: This first clinical experience with this new implant is stimulating, since it provides a reliable fixation, even into the osteopenic bone.

Purpose: We tested the reliability of a digitalised x-ray reading system, Imagika(r), used to measure linear wear of total hip arthroplasy on the AP view of the pelvis.

Material and methods: Wear measurements were taken for total hip arthroplasties without cement (n=20) and with cement (n=19) using the distance between the centre of the acetabular cup and the femoral ball. The system delivered measures in hundredths of millimetres that were rounded off to the nearest tenth millimetre. For non-cemented implants, the centre of the acetabular cup was found automatically on the digitalised radiograms using the contour of the metal socket. For cemented cups, the centre of the cup was determined from five points situated on the metallic ellipse included in the polyethylene circumference. The software placed the point clicked by the reader on the adjacent intermediary zone showing the greatest contrast. Five observers read the radiograms twice at 15 day intervals. The observers were a young resident, a senior traumatology surgeon,and a senior surgeon specialised in hip surgery. Results were compared to determine inter- and intra- observer variability.

Results: Intra-observer variability was low since the standard deviation (at alpha error set at 5%) ranged from one tenth of a millimetre to six-tenths of a millimetre for four observers. It was higher (2 millimetres) for the fourth observer. The younger observers achieved the best reproducibility, to the order of a tenth of millimetre. Conversely, interobserver variability was high with standard deviation of several millimetres for an alpha risk of 5%. Comparing the two observers who achieved the best performances, the standard deviation of the measures was in the 3 to 4 millimetre range.

Discussion: Measurement precision was greater for cemented cups. Conversely, for press-fit cups, the contour of the head was sometimes difficult to distinguish even with optimal contrast and measurement deviations were to the order of one millimetre.

Conclusion: The reproducibility of the Imagika(r) system is insufficient to measure wear of total hip arthroplasty where the precision must be to the order of a tenth of a millimetre.

Aims: To study knee kinematics using a dynamic computer model of 2 cadaver knees obtained by bone morphing. Patellar kinematics was simultaneously investigated using transosseous pins. Method: Ligamentous injuries were done (dicision of the anterior cruciate ligament (ACL) and of the popliteus). While maintaining the foot in slight external rotation, femoral rotation was measured in relation to knee flexion in the intact and injured knee. Results: The screw home rotation between −5 and +5° was comprised between 8 and 10°. From 10° on, the lateral condyle roll-back induced 30° of femoral external rotation. Femoral rotation could be blocked by externally rotating the tibia. On the screen, the rollback of the lateral condyle and the lift-off of the medial condyle at the end of the flexion appeared clearly. The patella rotated about its longitudinal axis. Moreover, it made a lateral translation. At deep knee flexion, it contacted mainly the lateral condyle. Dicision of the ACL decreased the screw home rotation to 3° and the femoral external rotation to 20°. At 110° and over, femoral rotation ceased, while both condyles rolled anteriorly. Dicision of the popliteus reduced the lateral condyle roll-back by 50%. Conclusion: 2 types of movement can be described: the end of rotation depending of the ACL; the external rotation of the femur depending on the popliteus.

Purpose: Dynamic MRI studies have confirmed the posterior displacement of the lateral condyle during flexion of the knee.

Material and methods: We used bone morphing navigation equipment to study knee kinetics in cadaver specimens and determine the effect of ligament injury. Patellar movement was controlled with pins. Femur movement over the tibia was measured by the navigation system during knee flexion.

Results: We noted external rotation of the femur during knee flexion when the tibia was maintained with the foot in the walking angle (15° with the flexion/extension plane), the femur being free to rotate. This rotation was nevertheless suppressed by constraining external rotation of the tibia. Unlocking rotation between −5° and +5° was measured between 8 and 10°. It was prolonged by greater rotation, increasing regularly with flexion to reach about 30° at 130° flexion. The computer display of the kinetics of the bony components demonstrated the posterior displacement of the lateral condyle. From 130° flexion, there was an elevation of the medial condyle which lost contact with the medial tibial plateau.

Posterior displacement of the lateral condyle was confirmed by rotation of the patella in its longitudinal axis. The patella appeared to make a lateral translation movement to come in front of the lateral condyle at near complete flexion. It pulled the vastus medialis as is suggested by its movement around the anteroposterior axis.

Section of the anterior cruciate ligament had little effect on the observed kinetics. It limited the unlocking rotation which did not exceed 3°. At about 110° the femoral rotation reached a plateau for about twenty degrees. The computer display illustrated the movement of the condyles showing that the movement of both was influenced by the posterior thigh soft tissue. Section of the popliteal muscle clearly lessened external rotation of the cadaveric knee.

Discussion: Two types of movement can be described: – external rotation of the tibia at the end of extension due to the influence of the anterior cruciate ligament; – facultative external rotation of the femur during flexion under the control of the popliteal muscle. This is expressed during single leg stooping and could protect the patella from excessive pressure by progressively displacing the lateral condyle.

Purpose: We report our first cases of retrograde nailing using the universal humerus nail (UHN).

Material and methods: Fifty patients (26 men and 24 women), mean age 60.2 years, with fracture of the humerus were treated with the UHN; most had shaft fractures, 40 were trauma victims, and ten had metastases.

Retrograde nailing was achieved by trepanation of the apex of the olecranon fossa. Proximal or distal locking was applied in all cases using one or more screws. Outcome was assessed with the S.O.O. criteria (1996).

Results: Two patients were lost to follow-up and two patients died early. Forty-six patients were reviewed with a mean follow-up of six months (range 3–18). Outcome was very good or good in 43 patients (bone healing at three months), fair in one, poor in two (two constructs dismounted at day 15); three asymptomatic fractures did not heal at one year (all healed two months after compression). Peroperative complications included: four fissures of the posterior cortical at the entry window and two supracondylar fractures. One patient developed radial palsy in the immediate postoperative period that resolved spontaneously. One of the proximal locking screws loosened early in four patients. Finally, one patient developed a supracondylar fracture at the point of entry following a fall four months after the nailed fracture had healed.

Discussion: The two cases of dismounting were subtuberosity fractures in elderly patients; likewise the one fair outcome was a minimal secondary displacement that had not healed at five months. The proximal locking screws did not hold well in osteoporotic heads explaining the three cases of early screw loosening. Impacting the curved nail into the last centimeters is a delicate operation and we had two fissures of the posterior cortical and peroperative supracondylar fractures early in our experience. Finally, the absence of an aiming device for the proximal locking screw complicates this procedure. The possibility for orthogonal proximal locking is however an advantage for rotatory stability. This nail allows early rehabilitation without mobilisation.

Conclusion: Retrograde locked nailing provides good results at three months for humeral shaft fractures. Subtuberosity fractures in elderly patients are not good indications. A straight nail would however be preferable and an aiming device for the proximal locking would be useful.

Purpose: We wanted to ascertain whether the advantages of functional treatment on trophicity could be combined with the advantages of surgical treatment on anatomic results in patients with displaced calcaneal join fractures.

Material and methods: Using the AO 3.5 reconstruction plates with specific stereotypic modelling we were able to obtain solid fixation in almost all cases of calcaneal joint fractures using a rigorous technique and following precise principles, notably the direction of the screw into the sustentaculum tali.As the osteosynthesis is very stable, we postulate that partial and progressive early weight bearing would be acceptable as long as pain was under a threshold level used as sign of micromobility. The first cases were very favourable so we extended this method, using it as a routine procedure for all cases (excepting those with an associated injury excluding weight bearing). Among 122 fractures operated with this method, 118 were reviewed.

Results: According to the Duparc classification, we treated one type 2, 34 type 3, 76 type 4 and seven type 5 fractures. Weight bearing was initiated on the average at 14 days, with a median of seven days. The Boehler angle improved from 0° preoperatively to 22° postoperatively. We did not have any cases of secondary displacement greater than 2°. The functional outcome was, according to the SOFCOT criteria: very good 34.5%, good 41.4%, fair 9.5% and poor 0%. Physical results (SOFCOT criteria) were: very good 17.2%, good 54.3%, fair 26.7%, poor 1.7%. Anatomic results according to AFC criteria were: very good and good 69%, fair 25.9%, poor 5.1%.

Discussion: These result demonstrate that a rigorous therapeutic management scheme can combine the advantages of functional and surgical treatment of displaced calcaneal joint fractures. Early weight-bearing below the pain threshold was effective since all our bilateral cases could be discharged after walking a few steps. Recovery was more rapid when weight bearing was late. Crutches could be abandoned at two months on the average.

Conclusion: We believe that solid osteosynthesis is possible in almost all cases of displaced calcaneal fractures with joint involvement if a rigorous technique is used. Progressive early weight bearing below the pain threshold is a significant adjuvant factor favouring rapid and quality outcome.

Purpose: The purpose of this work was to demonstrate the presence of polyethylene particles at the fixation interfaces of the femoral and acetabular components of non-dislocated cemented hip prostheses that had functioned in vivo for several years.

Material and methods: Three femoral components and two acetabular cups were recovered in two patients who died from an intercurrent cause. The first patient, an 85-year-old woman, had had a hip prosthesis for eight years. There was no radiological sign of displacement nor cup wear (stainless steel /polyethylene cup). For this same patient, the other hip had be revised for acetabular loosening three months prior to death. The femoral component was not loosened; it had been removed with its cement then reimplanted within the same cement sheath that was not removed. The cement/bone interface was thus preserved at eight years. In the second patient, a woman aged 88 years, the delay was nine years. This patient had no radiographic sign of loosening. The polyethylene acetabular insert exhibited 1 mm linear wear. This was a ceramic /polyethylene cup. The specimens were prepared by decalcification and defatting then fixation in buffered formol (pH 7.2) before embedding in polymethyl-metacrylate. After hardening, a diamond-tipped diatome to obtain transverse section of the femur at four levels: lesser trochanter, 2 cm below the lesser trochanter, 1 cm above the tip of the stem, 1 cm below the distal tip of the stem. After polishing, the 50 μ thick sections were stained with Picrofuschin von Jienson. The polyethylene acetabular cups were prepared likewise. Polyethylene particles were counted under polarised optic microscope at each cement /implant and cement /bone interface using an image analyser (Histolab, microvision instruments, Evry, France).

Results: There was no evidence of a fibrous membrane between the bone and the cement. A 10 to 20 mm space was sometimes observed at the metal /cement interface. Polyethylene particles measuring 3 to 10 μm were found at both cement /bone and metal /cement interfaces, including at the distal femur level. Particles were observed in the cement at several sites.

Conclusion: Large-sized polyethylene particles migrate around non-displaced cemented implants, partidularly between bone lines, and can follow the cement poriosity.

Purpose: The combined effects of metaphyseal filling and implant surface (smooth or rough) on stress applied to the cement was studied using finite element analysis.

Material and methods: The cement-metal interface was modelised in stable then unstable situations at different degrees of metaphyseal filling. For each case, stress applied to the cement sheath and femoral corticals were tested as were rotation displacements of certain nodes chosen at critical sites in the proximal part of the stem and the bone. A first model produced a 3D representation of the femur exposed to physiological weight-bearing. The second mode represented a femoral metaphysis with the cement sheath exposed to rotation forces, critical for femoral prosthesis stability.

Results: With implants with a rough surface (cement adherence), bone stress increased with decreasing implant size and was basically concentrated in the distal part of the bone (diaphysis). On the contrary, for polished surface implants, bone stress increased with the size of the implant and was basically concentrated in the proximal part of the bone (metaphysis). Stress in the cement sheath was lower for rough surface implants. With the smooth implant, they were greatest in the metaphyseal part of the cement sheath, especially with prosthetic configurations we the most filling. When a rotation force was applied to the implant, shear forces in the cement were greater with a rough than a smooth surface implant. Compression forces in the proximal and anterior part of the cement sheath increased with the size of the implant. Proximal discontinuity of the cement sheath did not produce deleterious mechanical effects. The smooth surface implants produced higher compression forces than rough surface implants in the proximal part of the cement sheath. In addition, with smooth surface implants, traction stress was zero in the proximal part of the cement sheath.

Discussion: Use of smooth surface implants with optimal metaphyseal filling increases the rotational stability and allows a better fixation of the femoral stem in total hip arthroplasty, with a more physiological transmission of the stress forces to the proximal part of the bone. It produces greater compression force on the cement but less traction stress.