Dual mobility design use in preventing total hip replacement dislocation following tumor resection.

INTRODUCTION: Total hip replacement (THR) following hip tumor resection incurs a high risk of dislocation. We assessed the incidence of dislocation associated with use of a dual mobility cup,and the functional results achieved. HYPOTHESIS: Use of a dual mobility cup would reduce the risk of THR instability following hip tumor resection. MATERIAL AND METHODS: We analyzed dislocation rates in a retrospective series of 71 dual mobility cup THRs implanted following the resection of a tumor hip condition: 33 primary bone tumors and 38 bone metastases. The presenting pathology was diagnosed anatomically, and surgery classified in terms of adopted abductor system strategy. Functional results were assessed in terms of pain (analgesia on the World Health Organisation [WHO] scale), assisted walking and Musculoskeletal Tumor Society (MSTS) score. RESULTS: An overall rate of 9.8% dislocation was observed, taking into account all etiologies and contexts together. More precisely, this rate resulted from a compound figure of 5.2% in bone metastasis and 15% in primitive bone tumor. Dislocation risk depended lesson etiology than on the surgical management of the abductor system, being 3.5% in the case of abductor conservation, 9.5% in the case of abductor sectioning/reinsertion, and 18%in case of gluteus medius muscle or nerve resection. Functional improvement was consistently observed, especially in bone metastasis. At the maximal follow-up, 32 patients were not using analgesics, six were taking WHO class III analgesics, 10 class II and 23 class I. Mean MSTS score was 68.1% +/- 23.5% in bone metastasis and 59.6% +/- 17.5% in primary bone tumor.Fourteen patients could walk without assistance, 33 with a single cane, 15 with two canes and eight with a walker; one patient had not been able to resume walking. DISCUSSION: In these indications, dual mobility cups use lead to lower dislocation rates than those reported in the literature. It proved especially effective in the case of bone metastasis and consolidation surgery. In the case of primary bone tumor, it failed to prevent dislocation following acetabular resection, especially when involving the abductor muscles and/or abductor innervation, although it provided lower dislocation rates, comparable to those experienced with other techniques, when applied to limited resection. LEVEL OF EVIDENCE: IV. Retrospective therapeutic study.

[Total hip arthroplasty in patients with chronic renal failure transplant or dialysis]. / Arthroplastie totale de hanche chez l'insuffisant rénal chronique greffé ou dialysé.

PURPOSE OF THE STUDY: Total hip arthroplasty (THA) is generally proposed for renal transplant patients with invalidating hip disease. For patients on chronic dialysis, the few published series report a higher rate of complications. These patients are considered more vulnerable. We report the results of a retrospective mid-term analysis of 28 renal failure patients (37 hips) with THA comparing renal transplant recipients with chronic dialysis patients. MATERIAL AND METHODS: THA was performed on 37 hips in 28 patients with renal failure between January 1993 and 2004. Treatment for the renal disease was transplantation or chronic dialysis. Mean patient age at the time of the arthroplasty was 56 years. Nine patients had bilateral THA. At review, four patients had died and none were lost to follow-up. Mean time between transplantation and hip arthroplasty was 9.9 years. Among the fourteen dialysis patients (21 hips), five had had a renal transplant. Mean time from onset of dialysis to arthroplasty was 12.3 years. At mean postoperative follow-up of six years (range 24 months to 12 years), 24 patients were living. Thirty-five hips had no surgical history. Aseptic osteonecrosis was the dominant etiology (75% of operative indications in the graft group and 52% in the dialysis group). The preoperative Postel-Merle-d'Aubigné score was 7.6 in the dialysis group and 10.3 in the graft group. Most of the cups were not cemented (n=31, 84%), as were most of the stems (n=29, 78%). All survivors were reviewed. The PMA score was determined. RESULTS: Early postoperative complications in the dialysis patients were: deep vein thrombosis (n=3), pulmonary embolism (n=4), operative site hematoma (n=2) and immediate septic complication with prompt revision and preservation of the implants (n=1). For the graft group, complications were: early dislocation (n=2), lung disease (n=3). Four patients, all in the dialysis group, died. At review, the mean PMA score was 14.2 in the dialysis patients and 15.7 in the graft patients. There were no radiological signs of loosening, nor of polyethylene wear, and no ectopic ossifications could be identified. There were no late infections. DISCUSSION: In renal transplant recipients, total hip arthroplasty is a reliable treatment for hip disease, providing good mid-term results and a morbidity close to that observed in the general population. Conversely, dialysis patients have a greater perioperative morbidity. Use of non-cemented implants is not associated with a higher rate of loosening than with cemented implants. It can be recalled that this type of surgery must be performed within the framework of careful pluridisciplinary patient management.

[Total hip arthroplasty after hip arthrodesis performed for septic arthritis]. / Désarthrodèse-prothèse de hanche pour séquelle d'arthrite septique: apropos d'une série de 17 cas à 6 ans de recul.

PURPOSE OF THE STUDY: Revision total hip arthroplasty (THA) after hip arthrodesis is an uncommon and challenging operation. The task would appear to be even more difficult if the arthrodesis was performed because of septic arthritis due to the theoretical risk of recurrent infection. We report our fifteen-year experience. MATERIAL AND METHODS: This retrospective study concerned 17 procedures performed in 17 patients (11 women, 6 men) between 1988 and 2003 on 5 right and 12 left hips. All of the patients had arthrodesis for sepsis: eight subsequent to tuberculosis and nine subsequent to septic arthritis (Staphylococcus aureus). We examined the impact of the initial arthrodesis (surgical technique, position, leg length) on neighboring joints and indications for de-fusion. Mean age was 53 years (range 32-74) and on average, the patients had a fixed hip for 36 years (range 7-59). Mean follow-up was six years (range 11 months to 15 years). Revision surgery was performed via a posterolateral approach for 12 hips (nine trochanterotomies) and via an anterolateral approach for five hips for implantation of nine cemented implants, six press fit implants, and two hybrid implants (cemented cup and press fit stem). Clinical assessment at last follow-up noted pain, walking capacity and joint motion. Leg length discrepancy was measured and complications were noted. RESULTS: The position of the original arthrodesis was considered satisfactory (flexion 20 degrees , adduction 0-10 degrees , external rotation 0-20 degrees ) for eight hips; leg length discrepancy was 4 cm (2-8 cm). Neighboring joints involved concerned the lumbar spine in 15 patients, the ipsilateral knee in ten patients, the contralateral knee in eight and the contralateral hip in six. The decision to remove the arthrodesis was based on functional needs related to lumbar pain (n=6), the homolateral knee (n=10, limping and leg length discrepancy), or an operation on the ipsilateral knee. After surgery, 14 hips (83%) were free of pain with improvement of the lumbar pain and pain of the homolateral knee. Six patients walked without support but 16 still had a limp. Flexion was 78 degrees . Leg length discrepancy was 2.5 cm on average and seven patients had balanced limbs. The postoperative period was uneventful for 14 of 17 patients (one paresia of the common fibular nerve, one femoral phlebitis, one early infection). Six late complications were noted: nonunion of the greater trochanter (n=2), recurrent ankylosis (n=1) and loosening (n=3). DISCUSSION AND CONCLUSION: An earlier history of infection does not appear to be a contraindication for implantation of a total hip arthroplasty after hip arthrodesis. Despite the long recovery period and the modest gain in joint motion, 80% of patients were satisfied after having had a blocked hip for 36 years on average.

[Aspergillar prosthetic hip infection with false aneurysm of the common femoral artery and cup migration into the pelvis]. / Infection aspergillaire et faux anévrisme mycotique fémoral au cours d'un descellement de prothèse totale de hanche avec migration intra-pelvienne de l'implant acétabulaire.

We report a case of Aspergillus fumigatus infection of a total hip arthroplasty. This rare infection was demonstrated at surgical revision of a loosened prosthesis with migration of the cup into the pelvis associated with a false aneurysm of the femoral artery. A vascular time was required before the orthopedic revision. This case illustrates the importance of the preoperative work-up in the event of cup migration. The double approach was required in our patient to control and repair the vascular structures. The difficult treatment of Aspergillus fumigatus is also discussed.

[Total hip arthroplasty after treatment of acetabular fracture]. / Arthroplastie de hanche pour séquelle de fracture de l'acétabulum.

PURPOSE OF THE STUDY: The aim of this retrospective analysis was to examine complications and technical difficulties observed during implantation of total hip arthroplasty (THA) after treatment of an acetabular fracture. MATERIAL AND METHODS: Forty patients (thirty men and ten women), mean age 50 years, were included in the study. The acetabular fracture had been treated surgically in 23 and orthpedically in 17. Mean time from initial trauma to implantation of the THA was eleven years. Hydroxyapatite-coated cups were inserted without cement in 32 patients. Cemented cups in eight (with two Kerboull cross, one Muller ring, and five simple polyethylene). Five femoral stems were cemented. Preoperative planning was designed to restore the center of the initial hip rotation to avoid excessive cup medialisation. Acetabular defects found intra-operatively were significantly greater in the group of patients treated orthopedically than in those treated surgically (p = 0.02). Autografts were thus used more frequently in the former (65%). RESULTS: One patient presented an intraoperative complication. The postoperative complications included phlebitis (n = 1), infection (n = 1), fibular nerve paralysis (n = 2), dislocation (n = 4), and heterotopic ossification (n = 7). The rate of postoperative complications was significantly higher in the group of patients treated surgically (52.2% versus 17.6%, p < 0.02). At last follow-up, mean 52 months, the mean Postel-Merle-d'Aubigne function score was 16.7. The rate of acetabular revision was 15% with four cemented cups being replaced at more than ten years due to aseptic loosening. Two press-fit cups were replaced early for infection in one patient and disassembly in another. DISCUSSION: Despite the high rate of complications, the mid-term results were good, encouraging us to continue this procedure as the first intention treatment using either a press fit cup with or without an autograft, or a cemented cup with a metal ring (Kerboull or Burch-Schneider).

[Desmoplastic fibroma or bone desmoid tumor: two cases]. / Le fibrome desmoplastique ou fibrome desmoïde osseux: à propos de 2 nouveaux cas d'une tumeur osseuse rare.

Desmoplastic fibroma or desmoid bone tumor is a rare tumor described for the first time by Jaffe in 1958. It accounts for 0.1 to 0.3% of all benign bone tumors. To date, about 150 cases involving the locomotor system have been reported. Histology is required for certain diagnosis of desmoplastic fibroma. The tumor is composed of sparse fibroblasts in a rich background of collagen fibers, a histological presentation exactly the same as soft tissue desmoid fibroma. We report two new cases of desmoplastic fibroma of the locomotor system. The observations illustrate the radiological diagnosis. MRI was used to search for local extension in bone or soft tissues. Biopsy is necessary to confirm the diagnosis. The histological presentation may be difficult to recognized and distinguish from low grade fibrosarcoma. After treatment, the rate of local recurrence is high in the event of partial resection. Surgery is the optimal treatment, with tumor resection as wide as possible depending on the localization.

Conformity to clinical practice guidelines, multidisciplinary management and outcome of treatment for soft tissue sarcomas.

BACKGROUND: The primary management of adult soft tissue sarcomas (STS) is characterized by heterogeneity across centers. Several studies suggest that it is improved when coordinated by specialized sarcoma centers. PATIENTS AND METHODS: This study, comparing STS patients of the Rhône-Alpes region treated within and outside the cancer network, retrospectively assesses the conformity of medical practice with 'evidence-based medicine' (EBM) reported under the clinical practice guidelines (CPGs) of the French Federation of Cancer Centers. Institutional records of 100 new STS patients seen between 1999 and 2001 in the regional comprehensive cancer center and Lyon University hospital were analyzed retrospectively (50/300 new files randomly selected in each institution). Medical decisions were checked for conformity with CPGs. RESULTS: Median age was 58 years (range 18-88) and median tumor size was 9 cm (range 1-26). The most common primary sites were extremities, viscera or trunk. The most frequent histology was leiomyosarcoma (21%) or liposarcoma (12%). Only 7% of cases were reviewed by formal multidisciplinary committee before biopsy (with 42% pre-surgery biopsies only). The first surgical resection was R0, R1 and R2 in 26, 29 and 45% of cases, respectively. Conformity to CPGs was rated 52, 81, 94 and 95% for initial surgery, radiation therapy, chemotherapy and follow-up, respectively. At multivariate analysis, pre-surgery multidisciplinary discussion, management in reference center and management within cancer network independently predicted conformity to CPGs. CONCLUSIONS: Conformity with EBM was similar to previous reports. Elaboration of treatment strategy within a formal multidisciplinary staff and treatment within a cancer network are both important prognostic factors for optimal clinical care.

[Cellular culture of osteoblasts and fibroblasts on porous calcium-phosphate bone substitutes]. / Culture cellulaire d'ostéoblastes et de fibroblastes sur substituts osseux poreux en phosphate de calcium.

PURPOSE OF THE STUDY: Calcium phosphate ceramics are synthetic bone substitutes able to fill in bone destruction as a support of the bone growth. This work consisted in an in vitro assessment of osteoblasts and fibroblasts cultures on macroporous calcium-phosphate bone substitutes to analyze the interaction between cells and bone substitute. MATERIALS AND METHODS: The macroporous ceramic was composed of 70% hydroxyapatite and 30% tri-calcium phosphate with known mechanical and physico-chemical properties. Three compounds were processed with different size of macropore and with or without microporosity on their surface. Cells were seeded on discs measuring 10 mm in diameter and 2 mm in thickness. Cellular viability was evaluated by the MTT test for every stage of observation. An histological study to observe the invasion in the depth of discs was performed. Scanning electron microscopy was used to analyze the cellular comportment in contact with the surface of substitutes. RESULTS: An exponential cellular growth was effective on each substitute with the two cellular types. Cells spread on the surface of the compounds covering macropores and colonized the depth of the discs. A size of macropore of 300 microm or more seemed to support this invasion. 15 microm sized interconnections appeared to be effective to allow cell migration between macropores. The cell proliferation was similar on substitutes with or without microporosity. CONCLUSION: Biomaterials currently used as bone substitute are more or less osteoconductive but they have no osteoinductive property. A hybrid association of calcium-phosphate ceramic with osteogenic cells should promote the development of a calcium phosphate compound with osteoinductive capacity.

Effect of micro- and macroporosity of bone substitutes on their mechanical properties and cellular response.

The control of porosity morphology and physico-chemical characteristics of calcium phosphate bone substitutes is a key-point to guaranty healing success. In this work, micro- and macroporosity of materials processed with 70% Hydroxyapatite (HAP) and 30% beta-tricalcium phosphate (beta-TCP) were controlled by sintering temperature and porogen addition, respectively. Porosity was quantified by scanning electron microscopy (pore size) and mercury intrusion porosimetry (interconnection between pores). The content of macrointerconnections and their size were dependent on porogen content, shape, and size. Mechanical properties (compressive strength) were strongly dependent on macroporosity size and content, on the basis of exponential laws, whereas microporosity ratio was less influent. Relying on those results, three types of materials with contrasting porous morphologies were processed and assessed in vitro, in primary culture of human osteoblasts and fibroblasts. With both types of cells, an exponential cellular growth was effective. Cells colonized the surface of the materials, bridging macroporosity, before colonizing the depth of the materials. Cell migration across and into macroporosity occurred via the emission by the cells of long cytoplasmic extensions that hanged on microporosity. Both macroporosity and macrointerconnectivity size influenced the penetration of cells. An interconnection size of 15 microm appeared to be effective to support this invasion without bringing down mechanical strength.

[Surgical treatment of acetabular fractures: outcome in a series of 60 consecutive cases]. / Traitement chirurgical des fractures de l'acétabulum: résultats d'une série continue de 60 cas.

PURPOSE OF THE STUDY: The aim of this study was to analyze clinical and radiographic results after surgical treatment of acetabular fractures. MATERIAL AND METHODS: We reviewed 60 consecutive fractures of the acetabulum with loss of joint congruency at mean 5-years follow-up after treatment. There were 49 men and 11 women, mean age 41 years. According to the R.O. grading, the fractures were: 22 class A (33.3%) including 17 type A1, 23 class B (38%) including 10 type B1a2, 14 class C (23.3%) and 1 unclassifiable. Eight of the patients had associated pelvic injury, 40 had hip dislocations and 9 had sciatic nerve injury. Ten femoral head fractures were discovered during the surgical procedure. Three surgical approaches were used: 1) Kocher Langenbeck approach (28 cases), 2) Mears and Rubash triradiate approach (8 cases), 3) extended iliofemoral approach (22 cases), 4) other approaches (2 cases). Anteroposterior and 45 degrees oblique view of the pelvis were obtained for all patients following admission. Computerized tomography scans were performed in all cases. Fracture displacement and congruency of the femoral head with the roof were documented according to the SOFCOT radiographic criteria. The quality of reduction was assessed using the Matta criteria and the Duquennoy and Senegas criteria. Clinical outcome was assessed at follow-up using the Postel-Merle-d'Aubigné score. RESULTS: Anatomic reduction was achieved in 62% of the cases (1 mm or less displacement on all views) and congruency of the femoral head with the roof was excellent in 73% of the cases. Clinical outcome was satisfactory in 80% (excellent or good). Operative complications included significant ectopic bone in 21, and in 2 others sciatic nerve palsy that had resolved at 1 year follow-up. Three patients developed avascular necrosis of the femoral head. DISCUSSION: Clinical outcome depends on the quality of the reduction. Class C and class B fractures with roof injury should thus be treated by large surgical exposure. The triradiate approach increases the incidence of ectopic bone. The higher incidence of ectopic bone in patients treated by osteotomy of the trochanter compared with patients without osteotomy of the trochanter was significant (p<0.05). Avascular necrosis of the femoral head was associated with delayed reduction (66% of the cases). CONCLUSION: Our good clinical results are encouraging; we are pursuing the use of surgical treatment for displaced acetabular fractures. Clinical outcome depends on the use of the appropriate surgical approach.

[Unstable pelvic ring fracture: osteosynthesis of the posterior lesion by percutaneous sacroiliac fixation]. / Fractures instables de l'anneau pelvien: ostéosynthèse de la lésion postérieure par vissage sacro-iliaque percutané

PURPOSE OF THE STUDY: We report our experience with percutaneous sacroiliac screwing for unstable pelvic ring fracture. MATERIAL AND METHODS: Twenty unstable pelvic ring fractures with sacroiliac disjunction (9 cases), trans-sacral fracture (9 cases), or bilateral posterior fractures (5 cases) were managed with percutaneous sacroiliac fixation using 1 or 2 screws. There was also pubic disjunction in 7 cases, managed by osteosynthesis in 5 cases. No fixation of fractures of one or both of the obturator rings, present in 13 cases, was attempted. The posterior screwing was performed under fluoroscopic guidance in 15 cases and computed tomographic guidance in 5. RESULTS: There were no infectious or neurological complications. Radiographically, anatomic reduction of the posterior fracture was achieved in 10 cases. A vertical ascension persisted in 4 patients and a rotation in 6. Radiographic results were correlated with delay to surgery: correction of the vertical displacement was achieved in 80% of the patients operated before five days and in 55% of the others. Two patients experienced a secondary displacement. There was no cases of nonunion of either the anterior or posterior fracture. Follow-up was available for 14 patients (2 patients died and follow-up was too short for 4). The mean Majeed score was 92/100 and none of the patients experienced anterior pain. Three patients had moderate pain in the sacroiliac area. DISCUSSION: The ventral position appears to be best adapted for percutaneous sacroiliac screwing but can be contraindicated by concomitant lesions. We prefer fluoroscopic guidance for these emergency procedures. Two views, ascending and descending, appear sufficient. The better stability provided by two screws can be achieved under computed tomographic guidance without risk of neurovascular damage. CONCLUSION: Percutaneous sacroiliac screwing is a good management strategy for unstable pelvic ring fractures with little risk of morbidity.

Radiologic anatomy of the spinal dorsal horn at the cervical level (anatomic-MRI correlations).

The spinal dorsal horn is known for its important functional role in the field of transmission and modulation of sensory afferents. Because of this, the dorsal horn represents a target for numerous analgesic and antispastic procedures. Thus, it would be interesting to develop imaging dedicated to this spinal structure. The purpose of this study was to investigate the radiologic anatomy of the cervical dorsal horn by magnetic resonance imaging (MRI) (1.5T). The first step consisted in the validation of the anatomic information provided by MRI on 5 human cadavers. A spin-echo sequence (T2, 2000/45) enabled the demonstration of good correlations between histologic sections and axial MRI slices performed at the corresponding cervical levels. The second step was the <> exploration of 20 subjects, aiming at the development of a gradient echo sequence (T2*) with a conventional MRI unit, compatible with a routine clinical examination. The dorsal horn was clearly identified in 77% of the axial slices performed (n = 300). The angle between the dorsal horn axis and the sagittal plane was measured as from 25.5 degrees at C2 to 40 degrees at C8 segments. The results of this anatomico-radiologic study of the cervical dorsal horn suggest that preoperative MRI could be useful to design the surgical approach to this structure, as performed during cervical microsurgical drezotomy (DREZ = dorsal root entry zone) for the treatment of selected cases of chronic pain or disabling spasticity in the upper limbs.

Locating the center of rotation of the hip.

In prosthetic surgery of the hip joint it is essential to recenter the hip to recreate the leverage of the gluteus medius muscle. Determination of the center of rotation of the hip is difficult if both hip joints have been destroyed. On the basis of 70 frontal radiographs of the hip in the standing position, the authors measured the position of the center of the femoral head in relation to Köhler's line and the TD line joining the two radiological Us ("tear-drops"). On the same radiograph they defined the horizontal and vertical indices. The descriptive analysis of these parameters stresses the influence of sex on the coordinates of the center of rotation of the hip. The authors demonstrated the statistical correlations between the coordinates of this center of rotation of the joint and certain horizontal and vertical indices. It emerged that knowledge of these indices suffices to define the theoretic position of the center of rotation. The method is compared with other principles set out in the literature. The procedure has a clinical application in the context of preoperative planning of prosthetic reconstruction of the acetabulum, whenever it is destroyed bilaterally (after trauma, in congenital dislocation or acetabular loosening, etc).

The left retro-aortic brachiocephalic vein: morphologic data and diagnostic ultrasound in 27 cases.

A left retro-aortic brachiocephalic vein is a rare anatomic entity. A retrospective study was made of 5218 congenital cardiopathies treated between 1982 and 1998 in a medico-surgical department of paediatric cardiology. A left retro-aortic brachiocephalic vein was demonstrated in 27 patients, i.e. an incidence of 0.5%. The chief cardiopathy in these patients was a tetralogy of Fallot in 25 cases (93%). Among these 25 cases of Fallot's tetralogy the aortic arch was rightsided in 19 cases (70%). The paraclinical diagnosis of this anomaly was facilitated by ultrasonography, provided it was sought for. In this series 6 cases (22%) were discovered during surgery without previous ultrasound diagnosis. The embryological origin of the left retro-aortic brachiocephalic v. differs from that of the venous trunk in its classical anatomic form. It derives from the inferior (but not superior) transverse plexuses, connecting the two anterior cardinal veins. One of the main consequences of this anomaly is its possible confusion with other vascular structures, particularly the right pulmonary artery. Such confusion may give rise to inappropriate surgical procedures. The differential diagnosis is facilitated by the use of the Doppler: the venous flow is biphasic and regulated by respiration, whereas the Doppler recording from a pulmonary artery is that of a characteristic systolic arterial flow.

[Total hip arthroplasty. Risk factors and prevention of iatrogenic vascular complications]. / Arthroplasties totales de hanche. Facteurs de risque et prévention descomplications vasculaires iatrogènes.

Vascular injuries during orthopaedic hip surgery are rare. However, they must always be feared because they threaten life and limb. We present 11 vascular injuries observed over a 12-year period. Seven women and 4 men, treated by elective surgery, presented 14 vascular injuries (6 arterial, 5 venous and 3 prosthetic vascular graft). Four injuries occurred during revision procedures. They were all operated as an emergency for ischaemic syndrome (6 cases) and/or haemorrhage (7 cases). Four patients (37%) died and 4 developed sequelae, various directly attributable to the vascular injury. In the light of these cases, we tried to determine the various mechanisms of the injury and the orthopedic and vascular risk factors. Preoperative detection and well defined therapeutic rules are very important for the prevention of these severe vascular accidents.

Morphometry of the talocrural joint.

Based on two orthogonal radiologic views, the authors present a morphometric study of the talocrural joint. In 50 normal subjects, 10 parameters were measured and divided into 3 groups: the distal tibial joint surface parameters, the malleolar parameters and the talar parameters. These parameters were treated in both a descriptive and a correlative analysis. If the talocrural joint is a hinge joint whose talar articular surface can be simplified and classed as a cylinder segment, it is possible to calculate its curve radius. Then the correlative analysis allows to define the talar parameters and the corresponding parameters of the distal tibial joint surface. The malleolar parameters are independent factors. This study is the first morphologic analysis to serve as a basis for an ankle arthroplasty.

Relationship between rearfoot and forefoot orientation and ground reaction forces during running.

In this study, footprint and ground reaction forces (GRF) were simultaneously recorded from 32 male subjects running barefoot. Angle between the rearfoot and the forefoot in static (alpha S) and in running (alpha R) conditions, and orientation of both, rearfoot (alpha rf) and forefoot (alpha ff) with the direction of running (DOR), were measured and correlated to selected GRF parameters. The dynamic rearfoot/forefoot angle (alpha R) was correlated, positively with arch deformation (r = 0.58, P < 0.001), vertical Fz loading peak (r = 0.60, P < 0.001), mediolateral, and anteroposterior force rates (r = 0.47 and 0.48, P < 0.01), and negatively with stance time (r = -0.41, P < 0.05) and total course of the force application point path (r = -0.71, P < 0.001). Both a medial and a lateral rotation were observed on footprint between the rearfoot and the forefoot in the horizontal plane. A medially rotated forefoot ("closed foot") was associated to a rigid and inverted foot, whereas a laterally rotated forefoot ("open foot") was associated to a flexible and everted foot.