Introduction: The anterior pelvic plane (APP), described by Lewinnek, is defined by the following points : anterior iliac spines, pubic symphysis. This plan is mostly considered as vertical in weight bearing and is currently used as the reference to guide cup insertion by means of imageless computer assistance (CAS). However, to our knowledge, there is no data that strongly confirm APP is vertical in weight bearing and how much his orientation is modified with regards operative position, or THA insertion. This study assessed these data by means of a radiological analysis.

Material and Methods: The orientation of the APP was measured with regards to the vertical plane on weight-bearing profile X-rays of the pelvis in 106 subjects including:

1) 82 patients with THA (40 who had at least one dislocation, and 42 matched patients without instability randomly selected, 19 of these 42 underwent a profile X-ray of the pelvis before and after THA insertion)

Results: Thirty-eight percent of the subjects in weight-bearing had an orientation of the APP different of more than ± 5° from vertical plane and 13% were out of the interval ±10°. The orientation of the APP was not significantly different between the groups (standard and THA) nor between the groups who had stable or unstable THA. The orientation of the APP was significantly modified between lying and weight-bearing posture, from a mean of 1,2° lying to −2,25° upright. Under these conditions, 12 subjects presented a variation of more than 7°. Insertion of a THA did not significantly modify the orientation of the APP in weight-bearing among the 19 subjects (variations were small (−1° ± 7° [from – 21° to 8°]), but were more than 5° for 7 of the 19 subjects).

Discussion and Conclusion: Most of the surgeons use the APP as a reference to guide navigation for cup insertion, considering it is vertical in weight-bearing. However, it is not true for 38% with a margin of 10°, which is equivalent to approximately half of the anatomical anteversion of the acetabulum. Standing up produced a significant variation of the orientation of the APP with regards to lying position. These errors that are not integrated by most of the CAS without preoperative CT scans, may produce cam effect or dislocation when the patient is moving to sited position. The variations of APP orientation with regards to vertical plane suggest it is not adequate to guide the CAS insertion of the cup. There is no reliable reference, easily identifiable during surgery that integrates the variations of position of the pelvis. This leads us to promote a new CAS for THA insertion free of reference plane, based on kinematics.

Aims: The goal was to determine if young patients respect the instructions for medical supervision control instructions after a total hip arthroplasty (THA). Methods:We performed 50 THA (Harris cups and ABG I stems) in 39 patients, mean age 38 years ± 11 (15–58). There were thirty-eight 28mm femoral heads (30 zirconia, 8 chromium-cobalt) and 12 chromium-cobalt heads in 22mm. Each patient was told how necessary a regular medical supervision was with the following schedule: controls at 2 months, 1 year then every two years. In 2000, all the patients were evaluated (no lost for follow-up). Wear was measured according to Livermore with a digitizer. Results: At 72 ± 14 months of follow-up (5–9 years), 51% of the patients (20/39) did not come back for the intermediate controls. No factor could be accounted for that, except being a male (p=0.04). Wear was rather severe (average 0.23 mm/year). 37% of the patients with a severe wear (> 0.2 mm/year) did not come back for intermediate controls and were all free of symptoms. There were 3 revisions because of wear (> 2 mm) and 3 others hips are awaiting revision because of wear. Three of these 6 patients did not come back for intermediate examination. The 28mm heads induced more wear than the 22mm heads (p=0.008). No other factor was related to how severe wear was (age, sex, activity or thickness of polyethylene inserts). Moreover the zirconia did not reduce wear. Conclusion: In spite of the recommendations, half of the patients did not respect the medical supervision schedule and that was unpredictable. We recommend a careful follow-up of young patients after a THA in order to detect wear (usually free of symptoms). Moreover our study underlined that the zirconia wasn’t so efficient to prevent wear phenomena.

Aims: Henri Dejour promoted a mechanism involving a third femoral condyle to achieve Posterior Stabilization (PS) in total knee arthroplasty (TKA) introducing the HLS II prosthesis. This retrospective study was conducted to assess the behavior of such PS mechanism. Methods: Between 1992 and 1993, 105 HLS II prostheses (94 patients) were consecutively inserted (78% arthrosis, 19% rheumatoid arthritis). No patient was lost for follow-up but 14 had died, 6 were unable to walk (severe neurological disorder), 4 were contacted by phone. Consequently, 70 patients (77 TKA) mean aged 66 years (22–79) were assessed after a mean follow-up of 7 years (6–8). All the components were fixed with cement and patellar resurfacing was always performed. Results: The knee IKS score increased from de 27 points [0–63] before surgery to 81 [21–100] at follow-up and functional IKS from 35 points [0–75] to 64 [0–100] (p< 0,0001). Similarly range of motion improved from 114° [60°–140°] to 116° [80°–135°] (NS). At follow-up, 86% of the patients were able to practice stairs (13% without support and 28% in alternative manner) against 52% before surgery (1% without support and 1% in alternative manner) (p=0,001). Tibial bone-cement radiolucencies were observed without loosening in 30% (all < 1 mm and non- progressive) mainly related to severe preoperative varus deformation (p = 0.01). One late infection required reoperation. Ninety months survival was 97% ± 1.3% with reoperation related to infection or mechanical disorder as end-point. Conclusion: The posterior stabilization, by means of a third condyle, allowed a satisfactory range of flexion and improved ability to practice stairs. Mid-term follow-up did not identified adverse effects of this PS mechanism on component fixation or knee stability.

Purpose: Posterior stabilisation with a third condyle was introduced by Henri Dejour with the HLSI prosthesis. While the posterior stabilisation process has been validated, this implant still raises some problems with the tibial fixation in patients with advanced joint degeneration, leading to the development of the HLSII model. The purpose of the present retrospective work was to evaluate functional outcome and persistance of the HLSII prosthesis fixation.

Material and methods: Between January 1992 and December 1993, 105 total knee arthroplasties (TKA) were performed in 94 consecutive patients using posterior stabilised HLSII prostheses. Indications were joint degeneration (40% stage 4) in 78% and polyarthritis in 19%. None of the patients were lost to follow-up but 14 patients died, six were bedridden (stroke sequela) and four were contacted by phone only. In all, 70 patients (77 TKA), mean age 66 years (22–79) were retained for clinical and radiological assessment at mean follow-up of seven years (range 6–8 years). All implants were cemented and the patella was resurfaced in all cases. Eight operators participated in this series. Junior surgeons (n=5) implanted one-third of the prostheses.

Results: The mean IKS knee score rose from 27±18 points (0–63) preoperatively to 81±18 (21–100) at last follow-up, function score from 35±20 (0–75) to 64±24 (0–100) (P< 0.0001). Motion changed from 114° (60–140°) to 116° (40–135°) (NS).Eighty-six percent of the patients used stairs (13% without handrail and 28% with alternate steps) versus 52% before the intervention (1% without handrail and 1% with alternate steps). (P=0.001). Knee alignment was normal ±5° in 87% of the cases versus 27% before surgery (P< 0.0001). Seventy-nine percent of the knees had a slope ±2° (desired slope 0°). The patellar retinaculum was sectioned in one quarter of the knees which led to four of the five postoperative haematomas (no revision). Five patellar fractures were noted, including two with patellar loosening (revised) and one clunk (cured after arthroscopic release). Lucent lines observed under the medial tibial plateau in 30% of the cases (all < 1 mm) were more frequent in patients with more severe joint degeneration and genu varus preoperatively (P =0.01). There was no case of aseptic femorotibial loosening. One case of late infection (30 months) was followed by replacement arthroplasty. Survival rate, taking mechanical and/or infectious failure as the endpoint, was 97± 1.3% at 90 months.

Discussion: Good axial control emphasises the reliability of the instrumentation since one-third of the prostheses were implanted by junior surgeons. Improvements in tibial fixation with the HLSII appear to be effective, particularly for stage 4 degeneration. Long-term surveillance is however necessary. The femoropatellar joint can give rise to non-infectious complications and should be improved. The concept of posterior stabilisation with a third condyle authorises good flexion amplitude and favours use of stairs.

Purpose: A new radiographic classification of the femoral trochlea was proposed by David Dejour in 1998 to quantify the severity of bony dysplasia. The purpose of this work was to evaluate the reproducibility of this classification system and to determine its contribution to the identification of trochlea with a high-risk of femoropatellar instability.

Material and methods: Nine independent observers (one resident, four junior surgeons, four senior surgeons) with no knowledge of the patient’s history read 68 strict lateral views of knees with femoropatellar instability (53 objective instabilities (OI) and 15 potential instabilities (PI)). The classification system includes four types determined with three signs: crossing (defining the dysplasia and present in all four types), supratrochlear spike, double contour. The four types are: type A crossing alone, type B crossing and spike, type C crossing and double contour, type D crossing, spike and double contour. The kappa test was used to assess reproducibility and chi square test to analyse data by category.

Results: Twenty-one radiographs were excluded by one or several observers due to insufficient quality or the impossibility to identify the signs of the new classification. Interob-server reproducibility assess on 47 radiographs was fair (kappa = 0.48). The crossing sign was identified by the nine observers on the 47 radiographs. Reproducibility of identification of the spike was good (κ= 0.62), but was fair for the double contour (κ = 0.51). there was no difference in reproducibility by level of experience of the observers. The new classification system was not correlated with severity of femoropatellar instability: presence of spike 80% OI, absence of spike 67% OI; presence of double contour 74% OI, absence of double contour 75% OI.

Discussion, conclusion: This new classification system is more reproducibly than the former 3-type system proposed by Henri Dejour. The crossing sign and the spike are the most reproducible signs. There presence is however insufficient to quantify the dysplasia and predict the severity of the femoropatellar instability. A quantitative measure of the depth of the trochlea, which shows excellent reproducibility (interclass coefficient 0.65) could be added to better quantify the morphological anomaly and determine the most adapted treatment.

Purpose: The purpose of this prospective work was to determine: 1) the frequency of iliopsoas conflicts with prosthetic acetabular material in patients with a painful total hip arthroplasty, and 2) to determine the diagnostic features of this conflict and the results of an adapted therapeutic approach.

Material and methods: This prospective study was conducted between 1988 and 2000 in 206 painful total hip arthroplasties. Nine patients (4.%), mean age 50 years (38–65) had a highly suggestive clinical presentation (eight press-fit cups without cement, one metal-backed cemented cup). Mean delay to onset after implantation of the total hip arthroplasty was 7.3 months (1–48). The predominant clinical sign was groin pain triggered by active flexion of the hip with pain from 3° to 70°. For these nine patients, there was no sign of loosening and puncture had ruled out infection. The diagnosis was confirmed by sedation of the pain after extra-articular infiltration in contact with the anterior acetabular rim (rim overhang in six out of nine cases) under computed tomographic guidance.

Results: Therapeutic infiltration (xylocaine-slow release corticosteroids) under computed tomographic guidance provided complete sedation in four out of nine cases and partial sedation in one. Four patients experienced recurrence leading to terminal tenotomy of the iliopsoas which provided complete sedation in three and partial sedation in one. In all, seven of the nine patients achieved complete pain relief (four after infiltration including one recurrent case, and three after tenotomy). Physical examination at last follow-up did not disclose any loss of flexion amplitude of the thigh.

Discussion and conclusion: The delay to symptom onset was variable, but a symptom-free interval was always observed after implantation of the total hip arthroplasty. An anatomic factor (anterior cup rim) was not indispensable for diagnosis as it was confirmed in one of three cases with a positive infiltration test without rim overhang. The infiltration test was essential to confirm diagnosis and constituted the first therapeutic attempt which allowed complete cure in four of the nine patients. Tenotomy, indicated in case of recurrence, achieved complete cure in three of the four cases. The cup does not have to be changed necessarily to treat iliopsoas conflicts since infiltration or simple tenotomy provided complete cure in seven out of nine cases.

Purpose: Changes in the lever arm of the abductors is not always perfectly controlled during implantation of total hip arthroplasties. Its possible effect on the development of prothesis dislocation is not known. The purpose of this study was to evaluate the influence of the lever arm and its modifications on the development of prosthetic instability.

Material and methods: We analysed prospectively 73 total hip arthroplasties implanted via the posterolateral approach. The study group was composed of a consecutive series of 45 dislocated prostheses and a control group of 28 stable prostheses selected at random. The following measurements were made on the anteroposterior x-ray: 1) lever arm of the abductors, 2) femoral offset. These measures were compared with the healthy contralateral hip and when this hip was diseased or had a prosthesis, with the pre-implantation x-rays.

Results: None of the studied parameters was statistically different between the dislocated and stable prostheses. However, in the dislocated prostheses, the lever arm of the abductors before insertion of the prosthesis was shorter than in the control group (p = 0.04) suggesting the presence of a group of hips “at risk”. There was a correlation between the offset values and the lever arm values for the stable prostheses and for the healthy contralateral hips in both groups. Conversely, this balance was not found in the dislocated hips. The lever arm/offset ratio was calculated to determine if the ideal ratio influenced hip stability. This ratio was not directly related to the development of dislocation, but it was decreased for dislocated hips. This ratio was ideal for 75% of the stable prostheses and for only 53% of the dislocated prostheses.

Conclusions: We concluded that: 1) hips “at risk” of dislocation would have a shorter lever arm, 2) the lever arm or the femoral offset do not have a direct effect on dislocation, and 3) stable hip prostheses have a balance similar to that in healthy hips identified by a correlation between the lever arm and the femoral offset. We thus emphasise the importance of respecting these parameters although they are probably not the only factors influencing prosthesis stability. Allowable variations are small, demanding careful and precise operation planning.

Purpose: The aim of this study was to follow a prospective cohort of young subjects with total hip arthroplasties (THA) in order to determine 1) how they complied with instructions concerning the surveillance of their implant, and 2) determine factors affecting non-compliance and the potential consequences in terms of wear.

Material and methods: We implanted fifty Harris I cups with the ABG I stem in 15 young men and 24 young women (11 bilateral implantations) between 1991 and 1995. These patients were a non-consecutive prospective series of patients under 60 years of age (mean age at implantation was 38 ± 11 years, range 15–58 years). The ABG I stem was implanted when the femoral canal was cylindrical, other implants were chosen for other morphologies. 28-mm femoral heads were used in 38 cases (30 zircone, 8 chromium-cobalt, polyethylene thickness 8.6 mm, range 8.3–12.4). The patients were informed of the need for regular surveillance with controls at two months, and one year and then every two years. We re-evaluated all the patients again in 2000. Radiographic wear was assessed according to Livermore using a numeric table (OrthoGraphics).

Results: At mean follow-up of 72 ± 14 months (5–9 years), 20 of the 39 patients (25/50 implants) had not attended the intermediary consultations, but all were seen again for the systematic review made in 2000. There was no particular factor related to non-attendance other than male gender (p = 0.04). Wear was rather severe. Mean values were: linear wear 1.32 mm, 0.23 mm/an. Thirty-seven percent of the patients who had severe annual linear wear (> 0.2 mm) had not attended consultations, all were asymptomatic. The 28 mm head produced more volumetric wear than the 22 mm heads (p = 0.008). There was no other factor correlated with severity of wear (age, sex, activity, polyethylene thickness). This systematic revision led to: three replacements due to excessive wear > 2 mm and replacements planned for three others with > 2 mm wear. These six patients were asymptomatic and three of the six had never attended the planned visits.

Conclusion: Despite our recommendations, half of the patients did not comply with the planned surveillance protocol. Non-compliance being inevitable, we recommend regular systematic recalls to detect severe wear early, even in asymptomatic patients. In addition, our study demonstrated that zircone heads contribute little and confirmed the interest of 22 mm heads to limit wear phenomena.