Cartilage morphology assessed by high resolution micro-computed tomography in non OA knees.

OBJECTIVE: At the microscopic level, there is no established 3D method to measure cartilage volume and thickness. An easy, precise and accurate volume and thickness measurements of human cartilage has been developed from micro-computed tomography (micro-CT) images. DESIGN: In the medial tibial plateau of twenty nine left cadaveric knees classified as normal, vertical cores (7 mm in diameter) were extracted in three locations: lateral (LAT), medial posterior (MP) and medial anterior (MA). The cores were imaged in mineral oil with micro-CT (voxel size 10.2 µm) and were measured cartilage volume (Cart.Vol, mm(3)) and cartilage thickness (Cart.Th, mm) using a thickness plugin. Short term reproducibility and standard deviation (ST_RMSCV%, ST_RMSSD, mm) were determined. To assess accuracy, holes with diameters of 2 mm, 3 mm, and 4 mm were artificially generated and nominal and measured hole sizes were compared. RESULTS: Precision of Cart.Vol_ST_RMSCV% was 1.35%. The mean biases between nominal hole volume and measurements were -0.49 ± 1.5 mm(3) (2 mm), -0.41 ± 4.2 mm(3) (3 mm) and +0.34 ± 4.4 mm(3) (4 mm). ST_RMSSD was 100 times lower than the biological variation and the highest bias to measure volume was 24 times lower. Cart.Th results statistically differed among core extraction locations: 1.75 ± 0.28 mm (LAT), 1.84 ± 0.40 mm (MP) and 2.32 ± 0.41 mm (MA). CONCLUSION: With a standard laboratory micro-CT system, it was possible to measure cartilage volume and thickness with good precision and accuracy relative to the biological variation of the specimen cohort. Cartilage measurements from micro-CT probably will improve the knowledge of the relationship between cartilage and subchondral bone and may allow to better understand the OA process.

Total hip replacement in young non-ambulatory cerebral palsy patients.

INTRODUCTION: The everyday life of a non-ambulatory adolescent or young adult with cerebral palsy can be severely impaired by a painful or stiff hip. The usual surgical solutions such as proximal femoral resection (PFR) are not entirely satisfactory for pain relief, and are mutilating. HYPOTHESIS: A retrospective study assessed the impact of total hip replacement (THR) on such impairment, on the hypothesis that it is more effective than PFR in relieving pain, without aggravating disability. PATIENTS AND METHODS: The surgical technique consisted in implanting a dual-mobility prosthesis with uncemented acetabular component and cemented femur, after upper femoral shaft shortening and short hip-spica cast immobilization. Forty THRs were performed in 33 patients, including 31 with multiple disability. Follow-up assessment focused on change in functional status, pain, and range of motion. RESULTS: Mean follow-up was 5 years. Pain was more or less entirely resolved. Improvement in range of motion was less striking, and there was no significant change in functional status. There were 2 general, 2 septic and 10 mechanical complications, 6 of which required surgical revision. DISCUSSION: In non-ambulatory cerebral palsy, THR provided much better alleviation of pain than found with PFR treatment. It should be reserved for patients able to withstand fairly long surgery and with femur size compatible with implantation of a femoral component, however small. LEVEL OF EVIDENCE: IV, retrospective study.

Volume effect on biological properties of a calcium phosphate hydraulic cement: experimental study in sheep.

Injectable calcium phosphate hydraulic cements (CPHC) are a new family of bone substitutes within the class of bone reconstruction biomaterials. In this work, CPHC were tested in two consistencies (preset blocks or liquid paste) in an experimental model of cancellous bone defect in sheep. The defects were eight times larger than those investigated previously in rabbits. Three delays (12, 24, and 52 weeks) were used. Before death, a double label of oxytetracycline and alizarine was made intravenously. The distribution of implants was randomized, histomorphometric evaluation was performed and compared with micrographic observation, and optical microscopy of stained sections was performed either under visible, ultraviolet, or polarized light. The results were compared with spontaneous healing of empty defects and with a control group of normal cancellous bone from sheeps of the same age. No significant difference has been observed between premolded and injected implants. In the sheep model, the degradation and new bone formation rates are three times slower, compared with those observed previously in rabbits. New bone formation increased from 5.9% (12 weeks) up to 11.0% (24 weeks) in the empty defect group. In the cement groups, 28.3% new bone was obtained at 12 weeks, which seemed then to level off (27.8% new bone at 24 weeks). Cement residues appear as radio-opaque cylinders on microradiographs. In all cases, a radiolucent layer was observed at the cement/bone interface at 24 weeks. Stained sections showed the formation of a fibroconnective capsule around the residual cement, which presumably slows down new bone formation. Nevertheless, quantitative bone remodeling was accelerated in the cement group; mineral apposition as well as adjusted apposition rates were higher, and the formation period as well as the mineralization of osteoid tissue were faster compared with empty cavities and controls. These results point to higher osteoblast activity and better exchange with surrounding tissues in the defects filled with cement.

Association of porous hydroxyapatite and bone marrow cells for bone regeneration.

The preparation of hybrid material with osteoinductive capacity may be achieved by association of cultured autologous bone cells with a porous ceramic vehicle. We optimized culture conditions for rabbit marrow stromal stem cells (MSCs), notably by selection from batches of fetal calf serum. Rabbit MSCs formed colony-forming unit-ribroblastic (CFU-Fs) in vitro. Their alkaline phosphatase (ALP) activity was doubled in the presence of dexamethasone. Autologous rabbit serum allowed the formation of ALP-positive CFU-Fs, but results were highly variable depending on the rabbit. We tested the osteogenic potential of autologous cultured (with or without dexamethasone addition in the culture medium) and noncultured rabbit MSCs associated with a porous hydroxyapatite ceramic after a dorsal intramuscular implantation. Nucleated cells (10(7) or 10(8)/mL) were used for the preparation of autologous hybrid material. A significantly higher number of implants containing bone was obtained with a suspension of 10(7) cells/mL cultured in the presence of 10(-8) M dexamethasone. Some positive implants were also obtained with a suspension of 10(8) noncultured cells/mL. We demonstrated the feasibility of preparing rabbit autologous hybrid materials following a process for controlling culture conditions, cell characterization and cell/material association.

[Severe motor weakness associated with lumbar spinal stenosis. A retrospective study of a series of 61 patients]. / Les déficits moteurs sévères dans les sténoses lombaires. Analyse rétrospective d'une série de 61 patients.

PURPOSE OF THE STUDY: Severe motor weakness is a rather infrequent symptom in the course of lumbar stenosis. The objectives of this study are three fold: describe the motor deficit, evaluate the prognosis factors and determine the type of stenosis the most likely to be complicated by motor loss. MATERIAL AND METHODS: 61 consecutive patients with a mean age of 63 years, operated on for a lumbar stenosis and with a severe motor deficit have been retrospectively studied. The mean follow-up was 38 months. The overall functional result was evaluated according to a rating scale, specially developed in our unit for the follow-up of lumbar stenosis. The motor capacity was rated from 0 (complete paralysis) to 5 (normal strength). According to that scale the motor weakness was rated as 0, 11 times as 1, 11 times, as 2, 11 times and as 3, 28 times. The deficit was unilateral in 79 per cent of cases and multiradicular in 58 per cent of patients. Sphincter abnormalities were also present in 9 cases. In 9 out of 10 patients the motor deficit was in the L5 territory. Stenosis was extended to 3 levels in 30 cases and was focal in the remaining cases. Degenerative spondylolishthesis was disclosed in 20 patients. In 3 out of 4 cases decompression was performed after 3 weeks of motor weakness and within 3 weeks in the remaining cases. RESULTS: According to our rating scale the overall results were considered excellent in 29 cases, good in 21 cases and fair in the 11 remaining cases. There was no complication, and no postoperative worsening of the deficit was observed. Regression of motor weakness was complete 22 times, partial 29 times and null 10 times. In the eleven complete deficits with a 0 cotation one receded completely, 7 receded partially and no improvement was noted in the 3 remaining cases. 6 out of the 9 patients with sphincter abnormalities recovered completely. In this study favourable prognosis parameters were as follows: age under 62 years, monoradicular deficit, stenosis at one level and association with a discal herniation. In contrast, severity of the initial motor weakness, association with sphincter abnormalities, presence or not of degenerative spondylolisthesis, or of a complete block on the myelogram were not influential variables. Chances of recovery were statistically diminished when decompression was performed after 6 weeks. DISCUSSION AND CONCLUSION: No study dealing specifically with the postoperative outcome of motor deficit caused by lumbar stenosis has been published. However the rate of motor recovery (complete or partial) disclosed in our series is comparable with that found in other series dealing more generally with the overall post-surgery outcome. At our last follow-up, 82 per cent of our patients were considered as having an excellent or good result. It can be concluded that the existence of a motor deficit is not a major pejorative factor of the overall final functional result. Motor weakness is more frequently observed in elderly patients, in cases with degenerative spondylolisthesis, or when a discal herniation is associated with a bony compression. Chances of recovery are better, when the deficit is monoradicular, when the stenosis is focal, or associated with a discal herniation and when the patient is relatively young.

[Orthopedic treatment of consequences of upper limb spasticity]. / Les traitements orthopédiques des conséquences de la spasticité au membre supérieur.

Orthopedic surgery for upper extremity spasticity is based on a precise clinical evaluation with motor and sensitive and cognitive factors. Use of electromyography and lidocain or toxin is necessary. Surgical aims are classified as hygienic or functional. Surgical procedures are divided into neurectomies, muscle, tendon and joint procedures. Results, in spite of heterogeneous populations and nonstandardized assessments, are described about shoulder, elbow and hand.

[A glomus tumor of the toe: a pediatric case report]. / Une tumeur glomique de l'orteil : une observation pédiatrique.

SUMMARY: A glomus tumour of the third toe is quite rare in children. The authors report a clinical observation based on a misdiagnosis due to insufficient investigations, which led to a mistaken referral to a pediatric psychiatrist. Preoperative diagnosis requires a targeted MRI. Complete resection of the tumor results in an immediate resolution of the pain.

Gene expression in normotopic and heterotopic human bone: increased level of SP7 mRNA in pathological tissue.

Head injury-induced heterotopic ossification (HO) develops at vicinity of joints and in severe cases requires surgical intervention. Our previous study demonstrated high mRNA levels of osteocalcin (OC), type 1 collagen (COL1), osteonectin and RUNX2/CBFA1 in osteocytes and lining osteoblasts from non-evolutive HO compared to equivalent healthy cells from the proximal femoral shaft of patients receiving prosthesis. This allowed a first molecular characterisation of this pathological bone. The aims of this study is to extend the analysis to 10 more genes and determine those involved in the high OC mRNA level observed in pathological bone samples. RNAs were prepared from normotopic and heterotopic human bone samples digested by collagenase. After cDNA synthesis, mRNA levels were determined by real-time PCR and normalised using beta actin and glyceraldehyde-3-phosphate dehydrogenase. OSTERIX/SP7 expression was observed for the first time in human adult bone biopsies. In HO samples higher levels of SP7 (four- to sevenfold increase) and 1alpha,25-dihydroxy vitamin D(3) receptor (VDR) (two- to threefold increase) were observed compared to control samples. Moreover, SP7 level was correlated to OC and RUNX2 levels. In control samples, OC and SP7 levels were correlated. Our study further confirms that the involvement of SP7 in bone physiology is not only limited to the developmental step. Moreover, our results support the hypothesis that in HO the high level of OC expression could be due not only to an increase in RUNX2, but also in SP7 or VDR or to an imbalance in their respective activities.

Motor deficit in lumbar spinal stenosis: a retrospective study of a series of 50 patients.

Severe motor weakness is an infrequent symptom in the course of lumbar stenosis. The objectives of this study are threefold: to describe the motor deficit, evaluate the prognosis factors, and determine the type of stenosis most likely to be complicated by motor loss. Fifty consecutive patients with a mean age of 65 years, operated on for a lumbar stenosis and with a severe motor deficit, have been retrospectively studied with a mean follow-up of 38 months. The overall functional result was evaluated according to the Beaujon scoring system. The motor capacity was rated from 0 (complete paralysis) to 5 (normal strength). Prognosis factors were investigated with a multivariate analysis model. Motor weakness was rated as zero 11 times, as one 8 times, as two 8 times, and as three 23 times. According to our rating scale, the overall results were considered excellent in 25 cases, good in 17 cases, and fair in the 8 remaining cases. Regression of motor weakness was complete 15 times, partial 25 times, and null 10 times. In this study, favorable prognosis parameters of motor weakness recovery were as follows: association with a discal herniation, stenosis at one level, preoperative duration of motor weakness <6 weeks, age <65, and monoradicular deficit. In contrast, severity of the initial motor weakness, association with sphincter abnormalities, presence or not of degenerative spondylolisthesis, or of a complete block on the myelogram were not influential variables.

Histological aspects in bone regeneration of an association with porous hydroxyapatite and bone marrow cells.

The osteogenic potential of an association of two kinds of hydroxyapatite (HA) porous ceramics with autologous bone marrow cells cultured with or without dexamethasone (10(-8)M) addition in the culture medium and non-cultured rabbit marrow stromal stem cells (MSCs) was tested after 4 weeks of implantation in the dorsal muscles of spine in rabbit. A significantly higher number of rabbits with implants containing bone tissue inside pores were obtained with 10(7) cells ml(-1) cultured treated with Dex. In the HA porous ceramic using naphtalen as porogen agent, the bone recolonization remains only at the periphery of implants and in the second row of pores, while in the HA porous ceramic using polymethacrylate (PMMA) microbeads as porogen agent, the bone recolonization is observed in the depth of implants. In the PMMA HA group, the Krüskal-Wallis variance analysis between the rabbits is significantly different with the percentage of number of occupied pores and occupied pores with bone tissue is different (p<0.05).

Porous HA ceramic for bone replacement: role of the pores and interconnections - experimental study in the rabbit.

Hydroxyapatite (HA) porous ceramics are increasingly used in biomedical applications. Their physical characteristics, such as porous volume, require perfect control of the pore shape, as well as the number and the size of their interconnections. The aim of our study was to evaluate a new HA ceramic using polymethylmethacrylate microbeads (PMMA) as the porous agent. Four interconnection sizes (30, 60, 100 and 130 microm) with a 175-260 microm pore size and three pore sizes (175-260, 260-350 and 350-435 microm) for a 130 microm interconnection size were tested. Various HA implants were appraised by microscopic evaluation in a 4.6 x 10 mm rabbit femur cancellous bone defect 12 weeks after implantation. The best osteoconduction result was obtained in the center of the ceramic by means of a 130 microm interconnection size and a 175-260 microm mean pore size. Bone formation obtained within the pores was double that obtained in our previous study where naphtalen microbeads were used as the porous agents.