Using radiography and computer tomography (CT) we studied the morphology of 83 hips in 69 Caucasian adults with osteoarthritis secondary to developmental dysplasia of the hip (DDH). A previously published series of 310 hips with primary osteoarthritis was used as a control group. According to the Crowe classification, 33 of the dysplastic hips were graded as class I, 27 as class II and 23 as class III or class IV.

The intramedullary femoral canal had reduced mediolateral and anteroposterior dimensions in all groups compared with the control group. Only in Crowe class II hips was the femoral neck-shaft angle increased. The proximal femur had more anteversion in all the developmental dysplasia of the hip groups, ranging from 2° to 80°. Templated measurement of acetabular dimensions for plain radiography closely matched measurements taken by CT.

The results of our study confirm the observations previously confined to the Japanese population.

Purpose: Wrist fractures are often seen in elderly subjects who cannot generally tolerate aggressive fixation of unstable fractures. Percutaneous intra-focal pinning (Kapandji) is usually employed. The purpose of this study was to compare the classical treatment of unstable extra-articular fractures of the lower quarter of the radius with posterior displacement with a modified pinning technique.

Material and methods: This prospective radiological study concerned two groups of randomised patients aged 30 – 70 years who were hospitalised for surgical treatment of Pouteau-Colles fractures. In the first group, all patients were treated by the classical intra-focal technique using one or two dorsal pins and one lateral pin (group K). In the second group, all patients were treated by fixation with one or two infrafocal dorsal pins and a third pin inserted transfocally (group KM). Preoperative care, anaesthesia, and postoperative care (21 days immobilisation, pin removal at 45 days) were the same in both groups. The following anatomic measurements were made on the radiographs at day 1, 21, 45, and last follow-up: radial inclination on the lateral and AP views, bistyloid line.

Results: Group K included 49 patients, mean age 45 years. Group KM included 46 patients, mean age 54 years. There was no statistical difference between groups for age, gender, side, type of fracture. Radial inclination on the AP view was 19.2 (10–27 in group KM and 23.2 (19-30) in group. On the lateral view, radial inclination was 0 (−11 to 20) in group KM and −5.7 (−25 to 2) in group K. The proportion of bistyloid lines considered satisfactory was not different between groups.

Discussion: Infra-focal pinning can have limitations for maintaining reduction to bone healing. The Kapandji technique modified by use of a third transstyloid pin appears to provide better stabilisation of unstable fractures of the lower extremity of the radius, particularly in older subjects who cannot tolerate aggressive surgery. This preliminary study should be completed by a radio-clinical analysis in a larger number of patients to confirm these results.

Purpose: Most revisions of total knee arthroplasty (TKA) occur before the fifth year. The leading cause is prosthesis malalignment. Computer-assisted surgery is presented as a technique which improves implantation precision. The purpose of this study was to evaluate the radiographic quality of computer-assisted TKA implantation in comparison with conventional implantation.

Material and methods: A prospective randomised study was conducted with a total of 82 patients assigned randomly to conventional instrumentation (group 1) or computer-assisted implantation (group 2). The two groups were comparable for age, gender, body mass index, side, and preoperative femorotibial angle (HKA). The same surgeon operated all patients using the same cemented posterostabilised prosthesis. Radiographically, the HKA, the theta angle between the mechanical and anatomic femoral axis, the angle of the femoral and tibial implantations, and the posterior tibial slope were noted. All measures were taken by an independent operator who was unaware of the operative technique.

Results: There was no statistical difference in the HKA 177.5° in group 1 and 179.2° in group 2 (p=0.13); the theta angle was 6° in group 1 and 5.9° in group 2 (p=0.78); the femoral implantation angle was 90.3° in group 1 and 90° in group 2 (p=0.74); the posterior tibial slope was 3.5° in group 1 and 3.15° in group 2 (p=0.65). There was a statistical difference in the tibial angle, 87.3° in group 1 and 89° in group 2 (p=0.012).

Discussion: This study demonstrates a significant improvement in the navigation group for the position of the tibial implant and no difference for the femoral implant. This might be related to the cut guide which allowed more intra-operative adjustment for the tibia. Blood loss was equivalent in the two groups (503 mg) and operative time was longer in the navigation group (18 minutes).

Conclusion: It appears important to have specifically adapted cut guides for computer-assisted surgery and to reduce operative time.

Purpose: Implantation of a unicompartmental knee pros-thesis (UKP) via a short incisiosn was proposed to improve rapid postoperative recovery. But it is known that long-term survival is highly dependent on implantation quality. The purpose of this study was to evaluate the influence of implantation quality assessed radiographically and that of rapid recovery after unicompartmental arthroplasty using the conventional or minimally invasive approach.

Material and methods: A continuous series of the first 25 cases of UKP implanted using the minimally invasive approach (group 1) was compared with a homogeneous group of matched knees in a series of 145 UKP implanted with the same approach as used for total knee arthroplasty (group 2). The groups were comparable for age, gender, weight, and height. The same medial cemented UKP with a metallic tibial base plate was implanted in both groups. Postoperative radiographic measures included the overall mechanical axis, the femoral and tibial implantation orientations, and the posterior tibial slope.

Results: There was no significantly different between groups 1 and 2 for mechanical axis (3.6° and 4.7° respectively), tibial implantation angle (87° and 88°), or posterior tibial slope (2.6° and 2°). The femoral implantation angle was also comparable (2.3° and 2.9°) with the exception of one knee (9°) in group 1. Hospital stay, use of crutches and resumed activity were significantly shorter in group 1. Blood loss (222 and 244 ml respectively), postoperative pain (visual analogue scale), and full flexion at one year were comparable between the groups.

Discussion: The basic difference between the two approaches is the absence of patellar eversion and rupture of the extensor system with the minimally invasive method. This probably explains the more rapid recovery of function and activity in this group. The one case of significant femoral deviation noted in this group points out the need for greater care in positioning the specific guides for the short incision approach. To evaluate the long-term results of UKP implanted with the minimally invasive approach, the same criteria for patient selection and prosthetic implantation should be used.

Purpose: Impacted piecemeal allografts for nonce-mented hemispheric cups raises a problem of primary stability in the case of extensive bone defects. The high centre of rotation of the oversized cup further increases bone loss, requiring an extralong neck. The purpose of this study was to describe the use of impacted piecemeal grafts associated with a pressfit supporting ring with reposition of the centre of rotation.

Material and methods: The piecemeal grafts were impacted into the acetabulum to fill the defect. The hydroxyapatite coated ring was pressfit for primary stability then stabilised with axial screws in the upper paste. A distal hook on the obturator foramen repositioned the centre of rotation. The study group included 103 cases of acetabular reconstruction, including 34 for aseptic loosening and type 2 and 3 acetabular substance loss. Clinical and radiographic assessment was performed at 5 and 12 years.

Results: Mean patient age was 58 years, mean weight was 64kg. The Harris score improved from 53 points preoperatively to 88 points at last follow-up. Radiographically, there were no cases of cup migration according to the Massin classification, and the centre of rotation (Pierchon) was anatomic in 66% horizontally and in 44% vertically. There were two lucent lines in zone 2 and mean polyethylene wear was 0.015 mm per year. Graft integration (Conn) was identical to the host in 84% with disappearance of the interface in 67%. There were three dislocations treated without changing the implant and two revisions for infection.

Discussion: Several theoretical and clinical studies have shown that the high centre of rotation increases stress on the implants and decreased abductor force. The results obtained in this study with a maximum 12 year follow-up show that indications for this pressfit technique associating reposition of the centre of rotation, fixation for stability, and restoration of bone stock can be widened. Limitations are bone destructions with rupture of the pelvic girdle.

Introduction: Recent studies showed that the position of the center of rotation and the prosthetic neck may infl uence implant fixation in hip arthroplasty. The purpose of this study is to evaluate the use of modular necks and their limits to restore hip geometry after the arthroplasty.

Methods: The study radiographically evaluates 117 cases of unilateral hip arthroplasty using a modular neck / head concept (Wright Medical). The analysis evaluated on a weight-bearing frontal pelvis view: center of rotation, horizontal abductor ratio, and vertical abductor index, comparatively to the controlateral hip using the student’t test. On the computerized templates of the association effectively used in each case was measured: neck length, lever arm and neck anteversion.

Results: In craniopodal the center of rotation averaged 0.19 in women and 0.23 in men. In mediolateral it averaged 0.26 in women and 0.32 in men. The mean horizontal abductor ratio was 0.65 in women and 0.70 in men. The mean vertical abductor index was 6:..4° in women and 6.5° in men. The mean neck length was 55.2 mm, the mean lever arm 39.3 mm, and the 15° ante or retroverted neck was noted in 10 %.

Discussion and conclusion: Restoration of the center of rotation was more accurate in mediolateral than in craniopodal, with a higher location as previously noted in the litterature. Abductor function was correctly restored excepted for the vertical index in women, probably due to the large variations of pelvis width. The limits of modular necks are large hip dysmorphy where neck length averages 60 mm, lever arm 45 mm and neck anteversion requires 30° of correction.

Introduction: Minimally invasive surgery (MIS) has recently been proposed for unicompartmental arthroplasty to allow quick function recovery. The purpose of this study is to evaluate retrospectively the indications in which this technique would have been possible and successful.

Methods: The requirements for the minimal invasive technique are: a pre-operative flexion of 100° and a lesion limited to one compartment of the knee. The preoperative status, operative findings and clinical outcome of 160 cases of unicompartmental knee arthroplasty (MG, Zimmer) were analyzed to determine whether the criteria for MIS would have been possible.

Results: Preoperatively 12 knees had a flexion less than 100°. Postoperatively four of them had a limited flexion ranging from 90° to 100°. In 53 knees (33 %), peripheral osteophytes were removed on the opposite tibiofemoral joint. None of them were revised for progression of osteoarthritis. In 33 knees (21 %) a patelloplasty was associated to the procedure for peripheral osteophytes. Two of them were revised at 12 and 20 months for osteoarthritis progression.

Discussion: Removal of peripheral osteophytes can be successfully associated to the unicompartmental procedure when using a conventional surgical approach. In 96 of the 160 knees (60 %) MIS was not recommended either for limited preoperative flexion or for peripheral osteophytes. In 2 knees unicompartmental arthroplasty itself was not the correct indication and total knee arthroplasty would have been the right solution. Finally, in 62 of the 160 knees (39 %) unicompartmental arthroplasty using MIS was indicated. In conclusion unicompartmental knee arthroplasty may be either performed by conventional or minimal approach based on the preoperative clinical and radiological evaluation.

Purpose: The current concern to achieve 120° postoperative flexion in certain patients raises the problems of polyethylene wear, prosthesis stability, and surgical technique. The purpose of this clinical and radiographic comparative study was to analyse pertinent factors

Material and methods: We studied two groups of posterior stabilised total knee prostheses with mobile plateaux. In group A (23 knees), the plateau had rotatory and translation mobility. In group B (36 knees) the plateaux only had rotatory mobility and the posterior condyle was long. We studied clinical flexion before surgery and postoperatively at one year. The radiographic analysis included: mechanical axis, height of the articular space, patellar height, anteroposterior prosthetic surface. In both groups the patients had undergone medial parapatellar arthrotomy and had participated in the same rehabilitation programme.

Results: There was no statistically significant difference between the two groups for age, gender, weight, height, pre-operative diagnosis, or preoperative flexion (mean 120.8°, range 90–130° in group A and mean 120.7°, range 90–140° in group B). Mean postoperative flexion was 114.8° (50–140°) in group A and 130.4° (90–150°) in group B. The difference was statistically significant. There were two episodes of instability in group A and none in group B. There was no difference concerning the pre- or postoperative axis or patellar height. There was a difference in articular space height and anteroposterior prosthetic surface.

Discussion: The gain in flexion achieved in group B is related to the smaller anteroposterior prosthetic surface and the more systematic use of distractors to clear the posterior part of the knee. The design of the posterior condyle could also be involved, allowing better congruence beyond 120°. The difference in stability between the two groups could be related to a difference in the distance between the apex of the tibial attachment and the posterior stabilisation cam. This study demonstrated that increased flexion is possible after total knee arthroplasty in certain patients. It is related to surgical technique but also has direct implications for prosthesis design.

Purpose: The Oxford unicompartmental prosthesis has congruent joint surfaces due to use of a mobile meniscus whose upper part matches the sphere constituted by the femoral component. The purpose of this work was to report results in a series of 75 prostheses studied with mean follow-up of 12.4 years (range 10–14 years).

Material and methods: Mean age of patients was 65 years (38–84), with 67% women and mean body mass index of 28.7 (21.2–40.6). Patients gave their subjective assessment of the arthroplasty and the IKS scores were determined. Radiographically, the mechanical alignment of the lower limb was evaluated pre- and postoperatively on the full stance images. The Kennedy classification (4 grades) was used to assess passage of the mechanical axis through the knee.

Results: At last follow-up, three patients were lost and eight had died. According to their subjective assessment, 84% of the patients were enthusiastic or satisfied. The overall IKS score showed that 52% of the patients were above 180 points, 25% above 150 points. Mean varus was 11° (2–24°) preoperatively and 5.7° (5° valgus to 14° varus) at last follow-up. The mechanical axis passed in the sufficient correction zone (c or 2) in 77% of the knees, undercorrection zone in 17% and in the overcorrection zone in 6%.Seven prostheses were revised for mechanical failure: four for loosening, two for extensive degeneration, and one for pain giving a survival curve of 90% at 12 years. It must be added that two meniscal dislocations occurred, one early due to wound dehiscence and infection and one late, both after a fall.

Discussion: Most loosenings occurred early and at the tibial level. Defective alignment could be incriminated in one case. The other knees exhibited a reactive line under the tibial plateau. The rate of dislocation should probably decline with the use of progressive reamers, not available at the time of this series. Finally none of the prostheses were revised for wear, confirming the proper prosthesis design.

This comparative clinical and radiographic study evaluates the role of implant design and positioning on maximum postoperative flexion after TKR.

Two groups of cemented posterostabilised mobile prosthesis were studied. In group A (23 cases) bearing mobility was possible in rotation and translation. In group B (36 cases) solely rotation was possible and the radius of the posterior femoral condyle was larger. In both groups the same medial transquadricipital approach was used and the postoperative rehabilitation was identical.

There were no significant difference between the two groups for patient age, sex, weight and etiology. The average preoperative flexion was 120.8° in group A and 120.7° in group B. The average postoperative flexion at one year was 114.8° in group A and 130.4° in group B. Instability was noted twice in group A and none in group B. Radiographically there was no difference in mechanical axis or patellar height. There was a difference in joint line elevation and anteroposterior joint size.

Higher flexion angle may be related to smaller antero-posterior joint size, better posterior osteophytes removal and larger posterior femoral condyle radius. Greater stability correlates with greater jumping distance over the tibial post. This study showed that deep flexion can be achieved in some patients after TKR, with implications on surgical technique and implant design.

The objective of the present study was to analyse kinematics of subjects having a UKA during stance phase of gait, where the ACL was intact at the time of the operative procedure.

Femorotibial contact positions for nineteen subjects (15 medial UKA (MUA); 14 lateral UKA (LUA); HSS > 90, post-op > 3 yrs) were analysed using video fluoroscopy.

During stance-phase of gait, on average, subjects having a medial UKA experienced 0.8 mm of anterior motion (7.7 to – 2.3 mm), while subjects having a lateral UKA experienced −0.4 mm (0.9 to – 2.1 mm) of posterior femoral rollback (PFR). Eight of 15 subjects having a medial UKA and two out of four lateral UKA experienced PFR. Eight of 15 subjects having a medial UKA experienced normal axial rotation (average = 0.9 degrees) and one out of four subjects having a lateral UKA experienced normal axial rotation (average = −6.0 degrees).

High variability in the kinematic data for subjects experiencing an anterior slide and opposite axial rotation suggests that these subjects had an ACL that was not functioning properly and was unable to provide an anterior constraint force with the necessary magnitude to thrust the femur in the anterior direction at full extension. Progressive laxity of the ACL may occur over time, and at least in part, lead to premature polyethylene wear occasionally seen in UKA. Our results support the findings of other studies that the ACL plays a significant role in maintaining satisfactory knee kinematics, which may also, in part, contribute to UKA longevity.

The objective of this present study was to determine the in vivo kinematic patterns for subjects implanted with a patellofemoral arthroplasty (PFA).

Twenty subjects, all having a PFA, were studied (< 2 years post-op) under fluoroscopic surveillance to determine patellofemoral contact positions, sagittal plane, and medial/lateral translation using a skyline view.

The patellofemoral contact patterns for each subject having a PFA was highly variable, 11.9 mm of translation. The average amount of patella rotation during the full flexion cycle was 26.3 degrees, while one subject experienced 48.6 degrees. The average amount of medial/lateral translation was 3.8 mm (5 > 5 mm). Five subjects experienced grater than 5 mm of motion.

This was the first study to ever determine the in vivo kinematics for subjects having a PFA and the in vivo medial/lateral translation patterns of the patellofemoral joint. Subjects in this study experienced high variability and some abnormal rotational patterns. Most of the subjects who underwent PFA in this study had a previous history of subluxed or dislocated patella which affects the normal patella tracking, especially regarding tilting and translation. This tracking may also be directly affected by patellofemoral conformity, a consequence of femoral implant design. Finally, after PFA the patello-tibial tilt angle is influenced by the anteroposterior positioning of the femoral component.

The results of this very first in vivo kinematic study may play an important role, not only for design consideration of patellofemoral replacement but also for surgical technique in order to obtain optimal implant positioning.

Purpose: Implantation of a prosthesis on a remodelled femur can cause technical difficulties affecting the outcome of the arthroplasty. We performed a tridimensional study of the femoral anatomy before prosthesis implantation for sequelar congenital hip dislocation.

Material and method: The series included 312 hips in 262 patients. The same radiography and computed tomography work-up was perfomred in all patients. There were 288 women and 84 men, men age 56 years. Mean weight was 66 kg and mean height was 163 cm. The crowe classification was 195 dysplasia, 123 dislocations (41% class I, 27% class II, 13% class III, 19% class IV). Telemetric measurements were: femoral isthma, the centre of the lesser trochanter, limb length discrepancy, the cephalo-cervico-diaphyseal angle. Computed tomographic measurements were: anterio-posterior and mediolateral dimensions and femur funneling, helitorsion between the bichondylar plane and the upper femur, anteroposterior diameter of the acetabulum.

Results: The mean mediolateral and anteroposterior diameters of the femoral canal at the isthma were 9.8 and 13.1 cm respectively in dysplasia and 9.3 and 12.6 cm, 9.4 and 12.7, and 9.7 and 13.6 cm in I, II, and III–IV congenital dislocations respectively. The femoral funneling index varied from 1.9 to 7.6 in dysplasia and from 2.6 to 7.9, 2.1 to 8.4 and 2.1 to 8.7 in I, II, and III–IV congenital dislocations respectively. The mean cephalo-cervico-diaphyseal angle was 129.3°, 131.9°, 136.8°, and 127.4° respectively. Maximal leg length discrepancy was 45, 57, 71, and 82 cm respectively. Mean helitorsion was 22.9° (1°–52°), 36.4° (8°–86°), 43.2° (2°–82°- and 38.4° (6°–68°) respectively. The mean anteroposterior diameter of the acetabulum was 52, 51.2, 53.1; and 49.6 cm respectively.

Discussion and conclusion: The dysplastic or dislocated femur is narrower than the normal femur with wide variations in funneling and cephalo-cervico-diphyseal angle. The mean difference in leg length increases gradually with helitorsion but with wide individual variability, irrespective of the grade. These tridimensional anatomic data can be useful for predicting difficulties in prosthetic treatment of these patients.

We recovered 23 meniscal bearings from 18 failed bicompartmental Oxford knee prostheses. They had been implanted for one to nine years. The minimum thickness of the retrieved bearings was measured and compared with the thickness of 25 unused bearings. The mean penetration rate, calculated by two methods, was either 0.043 or 0.026 mm per annum. This compares with 0.19 mm per annum reported for the Charnley hip. The use of a fully congruous meniscal bearing prosthesis can reduce wear in knee arthroplasty to a very low rate.

Biological fixation of cementless femoral implants requires primary stability by optimal fit in the proximal femur. The anatomy of the bone must then be known precisely. We analysed in vitro the accuracy of bone measurements of 32 femurs and compared the dimensions obtained from radiographs and CT scans with the true anatomical dimensions. Standard radiographs gave only a rough approximation of femoral geometry (mean difference: 2.4 +/- 1.4 mm) insufficiently accurate to allow selection of the best fitting prosthesis from a range of sizes and altogether inadequate to design a custom-made prosthesis. CT scans give greater accuracy (mean difference: 0.8 +/- 0.7 mm) in our experimental conditions, but in clinical practice additional sources of error exist.