Purpose of the study: The right position of total hip arthroplasty (THA) implants affects short-, mid- and long-term outcome and complications. Navigation can improve implant position relative to a reference plane, in particular during mini-invasive implantation. The purpose of this work was to compare the position of the prosthetic cup in two series, one implanted with a navigation system and one with the conventional technique.

Material and method: The same surgeon performed the operations in each group of 42 patients (matched for age, gender, BMI, side). In the historic non-navigated series, a press fit femoral implant was used (Excia). The cups were either press fit (Ovalock or Plasmacup), or cemented with polyethylene inserts. The Hardigne incision (15 cm) was used for the conventional implantations. In the prospective navigated series, a press fit femoral element (Excia) and a press fit cup (Plasmacup) were implanted. The Orhtopilot navigation system was used (reference plane: Lewinnek anterior pelvic plane). The adapted Hardinge incision (5 cm) was used for the mini-invasive implantations. Inclination was measured on the weight-bearing pelvis relative to the radiological U line; the Pradhan method was used for anteversion. The objective was to achieve 45° horizontal inclination and 15° anteversion.

Results: In the non-navigated series, the inclination was 53±8 and in the navigated series 44±5.6. On average, inclination decreased significantly (8). Anteversion in the non-navigated series was 7±4, and 12±5.3 in the navigated series. On average, anteversion increased by 6 (statistically significant). The number of cups in the Lewinnek safety zone was 21 of 42 (50%) in the non-navigated series and 38 of 42 (90%) in the navigated series (statistically significant). The increase in leg length was 6.2 mm in the non-navigated group and 4.4 in the navigated group.

Discussion: Positioning did not take into account the preoperative analysis of the hip, but could adapt to scanner or EOS data. Navigation should also integrate offset, femoral position, and leg length.

Conclusion: Navigation of the prosthetic cup improves precision positioning in relation to the reference objectives, in particular, for mini-invasive surgery.

Navigation technology is a new tool which can help surgeons to a more accurate hip component implantation and a better reproducibility of the procedure.

The purpose of this study was to compare conventional and navigated technique and a new developed straight hip stem for uncemented primary total hip replacement.

The results of two consecutive implantation series of 42 patients (non navigated) and 42 patients (navigated) were analysed for implant positioning and short term complications. Non navigated components were implanted through conventional incision (15 cm), navigated component by minimal invasive surgery (5 cm). All surgeries were performed through Hardinge approach and by a single senior surgeon.

Radiographic analysis of cup position showed a significant improvement with reduced radiological inclination (53° non navigated/44° navigated, p< 0.001) and higher anteversion (7° non navigated/12° navigated, p< 0.001). The mean postoperative limb length difference was 6.2 mm (SD 9.0, non navigated) and 4.4 mm (SD 6.4, navigated). Intraoperative and early postoperative complications were not different. No dislocation occurred in both groups. There was one intraoperative trochanter fracture which was not revised (non navigated) and one revision because of a periprosthetic fracture caused by fall down during rehabilitation (navigated).

We conclude that acetabular implant positioning can be significantly improved by the use of navigated surgery technique even in minimal invasive surgery condition. The data for postoperative limb length difference was still similar but within the expected range in both groups. Navigation technology seems essential for minimal invasive surgical procedure yielding help and security to the surgeon. The effect of improved cup positioning on mid and long term results for both groups have to be further investigated.

Introduction: A good cup positioning requires reliable anatomical landmarks expecially for navigation. The anterior pelvic plane (APP) seems to be a good reference for navigation because it is in relation with pelvic tilt which do affect the position of the cotyle and consequently the position of the cup. The value of this plane is not well known according to gender, age, weight… The aim of the study is to assess radiologically the APP in standing and supine position before and after total hip arthroplasty.

MATERIALS AND Methods: 92 Patients (32 males, 60 females, mean age 65 years) underwent strict lateral X-rays in standing and supine standardized position. Uninterpretable or unsatisfying X rays were withdrawn. 45 patients underwent a standing X-ray, 24 a supine X-ray, 21 a supine and standing X ray. Statistical analysis used a Student t-test.

Results: Non matched values showed a retroversion of the pelvis of 6.4° (+/− 6.9) in supine position, 0.3° (+/− 7.4) in standing position. Matches values showed an retroversion of the pelvic of 6.9° (+/− 5.3) in supine position, 0.3° (+/− 5.03) in standing position (significant difference). Extreme values varied from −15° to + 18° (3 patients showed no variation, 2 patients a retroversion from supine to standing position). There was no statistical difference between male and female but a statistical differences in females.

Discussion: The APP is easily assessable by X rays in standing as in supine position. Bony landmarks of the plane are also assessable by navigation tools and to can be a good plane as reference. Several authors showed the repercussion of the pelvic tilt on the cotyle position. The difference between standing and supine position is about 6°. But for some patients the difference is may be of 20°and that could explain some impigment and instability. A cup well positioned in supine position may be not so good in standing position because of the pelvic tilt.

Conclusion: The value of the APP is important to know before THA and seems to be a good plane as reference for navigation.

Purpose of the study: Correct positioning of the prosthetic cup requires reliable anatomic landmarks, particularly for navigation systems. Referring uniquely to the three dimensions fails to recognize interindividual differences in pelvic position. The anterior plane of the pelvis is a good indicator of the pelvic position which can be determined from radiographic measurements. Standard values are poorly known (age, gender, weight). The purpose of this study was to measure the APP radiographically in the upright and reclining positions before and after total hip arthroplasty and to correlate the observed values with those obtained with navigation and ultrasound.

Material and methods: Strictly standardized x-rays of the pelvis in the upright and standing position were obtained in 110 patients (40 men, 70 women, mean age 65 years). Films which did not meet strict standard criteria were removed from the analysis which thus included upright views in 57 patients, reclining view in 36, and upright and reclining views in 28. Navigation measurements were made in 20 patients and ultrasound measurements in 10.

Results: Before arthroplasty, anteversion was 6.42±6.9° in the reclining position, 0.29±7.39° in the upright position (significant difference). After arthroplasty, anteversion was 6.9±5.3° in the upright position and 0.28±5.03 in the reclining position (significant difference). The values ranged from −15° to +18° (three patients without change, four with anteversion). There was no significant difference by gender. There was no clear correlation between the navigation values and those measured on the standard x-rays. The navigation and ultrasound values appeared to be correlated.

Discussion: The anterior pelvic plane can be easily measured on standard x-rays (upright and reclining position). Its landmarks can be easily accessed by navigation enabling the constitution of a reference plane. Several authors have demonstrated the influence of pelvic tilt on the position of the prosthetic cup. Posterior tile produces acetabular anteversion and inversely. The difference between the reclining and upright position is to the order of 6°. There are however variants up to 20° observed in certain patients and which might explain malpositions or instabilities. A cup with correct anteversion in the reclining position may be malpositioned on the upright film because of pelvic tilt.

Conclusion: Pelvic tilt should be taken into consideration when positioning the cup. The anterior pelvic plane can be correctly measured on standard x-rays and used to evaluate this tilt then serve as a reference for navigation. It should be proposed in all patients to search for extreme values.

Purpose of the study: Static metatarsalgia is a common complaint in podology surgery. Most cases are related to the great toe, but in certain cases, isolated metatarsal disharmony, without hallux vlgus, can be observed. We report 45 such cases.

Material and methods: This was a retrospective analysis of isolated metatarsal disharmony observed in patients who underwent metatarsal surgery between 1986 and 2003. There were 36 women and 9 men, mean age 49 years. Three subgroups were distinguished: posttraumatic disharmony, isolated disharmony of the second ray, iatrogenic disharmony. Conditions related to rheumatoid disease, aseptic osteonecrosis of the metatarsal heads, and rear foot disorders were excluded. Surgical treatment was osteotomy of the base of the metatarsal for 24 patients, and Weil’s osteotomy for 21. Clinical and radiological assessment used the Kitaoko and Maestro criteria.

Results: Mean preoperative score was 38 (range 21–58). Mean gain one year after osteotomy was 35 points. The score was 76 after osteotomy of the metatarsal base and 79 after Weil osteotomy. The less favorable results were observed in the group of posttraumatic metatarsalgias. Outcom was less satisfactory in the male population where residual metatarsalgia was noted in 75%. Reflex dystrophy occurred in 15% of the patients who had multiple osteotomies. Radiographically, The SM4 line was centered with progressive geometry in 50%.

Discussion: While the short-term results obtained with these two surgical methods were similar, osteotomy of the metatarsal base offers better long-term outcome. The osteotomy improved the functional score, even without improvement of radiological criteria. Initial treatment of metatarsal fractures should attempt to restore correct alignment of the metatarsals because of the poor results obtained with corrective osteotomy for posttraumatic misalignment.

Conclusion: When metatarsal disharmony is symptomatic, we propose osteotomy of the base of the metatarsals for the median rays in order to avoid transfer metatarsalgia. Complementary osteotomy of the fifth metatarsal is not always necessary.

Purpose of the study: Percutaneous compression plating (PCCP) is a new method for minimally invasive fixation of intratrochanteric fractures. Fixation is achieved with two neck screws and a 3-hole plate. This prospective study of a non-randomized series was designed to compare results in a monocentric cohort of patients treated by PCCP or dynamic hip screw (DHS).

Material and methods: From September 2003 to December 2004, all patients presenting an A1 (75.8%) or A1 (24.2%) (AO classification) intratrochanteric fracture were treated with PCCP (n=37) or DHS (n=20). Female gender predominated (86.5%) in this elderly population, mean age 83.2 years. The following variables were studied: operative time, radiation time, blood loss, hemoglobin level, blood transfusion, bone healing, complications, quality of the reduction.

Results: Mean follow-up was 8.3 months. The two groups were similar regarding bone healing, functional outcome and mortality. Intraoperative blood loss was less with PCCP (63 ml) than with DHS (120 ml). Mean fall in hemoglobin level was 2 after PCCP and 3 after DHS. The transfusion rate was 28% for PCCP and 40% for DHS. Mean operative time was 50 for PCCP and 30 minutes for DHS. Men radiation exposure was 4 minutes for PCCP and 1 minute for DHS. The positions of the screw (DHS) and the two PCCP screws were considered good for 68% of the PCCP and 75% of the DHS, acceptable for 29% PCCP and 20% DHS, and poor for 3% PCCP and 5% DHS. Complications were similar (one disassembly in each group).

Discussion: Although this was a preliminary study, PCCP was found to provide an attractive alternative for the treatment of intratrochanteric fractures. Results are similar to those obtained with the DHS but with a less aggressive method (limited approach, less blood loss). A learning curve (at least 10 implantations) appears indispensable to achieve maximum skill. The main drawback is the duration of the radiation. This implant would not be acceptable for subtrochanteric fractures which would require another type of implant.