Journal of Musculoskeletal Research

This is a follow-up study of the surgical efficacy of posterior lumbar interbody fusion (PLIF) for degenerative spondylolisthesis. Over the past 17 years, the authors have applied 7 alternative forms of reinforcement/augmentation to the basic/simple PLIF in an attempt to minimize the rate of fusion complications such as graft collapse, delayed fusion and nonunion. Each variant of the PLIF, along with the basic PLIF was performed on a significant number of patients, yielding a large population for this study. Clinical, radiological and statistical analyses were performed to determine the success of each variant, the basic PLIF, as well as the efficacy of the PLIF in aggregate for cases of degenerative spondylolisthesis. 166 patients were enrolled in this study. The average post-surgical follow-up occurred at 60 months, with a range of 13–188 months encompassing all subjects. Group A (basic/simple PLIF with autologous iliac bone graft)'s rate of fusion complications was 50%. Group B (autologous graft with internal fixation) rate of fusion complications was 36%. Group C (VSP with intervertebral spacers) rate of fusion complications was 13%. The mean recovery rates increased in a stepwise fashion from Group A to B to C. The mean recovery rates in patients with optimal fusion was significantly higher than in patients with fusion complications. The authors conclude that rigid fixation and graft solidarity are essential for achieving optimal results when performing the PLIF. Optimal fusion was correlated with significantly better clinical results.

The aim of this study was to retrospectively review clinical outcomes of posterolateral fusion for 50 consecutive patients with unstable lumbar spine and to determine which radiological factors affect clinical results. Patients with poor outcomes were older and had a greater number of fused segments than did those with good outcomes. Except for these, there were no relationships between clinical preoperative factors and outcomes on follow-up examination. At follow-up, decrease in lordosis and increases in slippage and L1 axis S1 distance (LASD) (which was measured as the distance along the perpendicular axis from the center in the L1 body to the posterior superior edge of the S1 body) were found in patients with poor surgical outcomes. The slippage on follow-up examination was significantly greater in patients with LASDs above 35 mm, preoperatively, than in those whose LASD was less than 35 mm. The lesions of adjacent segments and bony union rate did not influence the clinical results. A preoperative radiological risk factor is LASD greater than 35 mm, which was associated with an increase in the slippage at follow-up. Maintenance of lumbar lordosis and an LASD below 35 mm and after the surgery, may improve clinical outcomes.

This study in rabbit knees was carried out to clarify the effect of the application of CPM, after meniscectomy, on the regeneration rate of the meniscus and histology of the regenerated menisci. Twenty-seven mature rabbits were used: three rabbits as control (non-CPM) and 24 rabbits as experimental ones. Among them, four rabbits were used as the immediate CPM group and 20 rabbits as the delayed CPM group. In each animal, the medial meniscus was totally excised from the right knee, and the lateral meniscus was totally excised from the left knee. In three control animals, 16 weeks after meniscectomy, there was (hold) Grade II to III meniscal regeneration in two, and small meniscal mold was formed in one. In the immediate CPM group, meniscal regeneration failed and there was would disruption in all four knees. In the delayed CPM group, grades II to III regeneration was observed in 15 of the 20 medial meniscectomized knees, while in the lateral meniscectomized knees, the same size of meniscal regeneration was observed only in 3 of the 20 knees. The regenerated menisci in the delayed CPM group overall looked normal in appearance. Application of the delayed CPM induced the early fibrocartilaginous metaplasia of the regenerated fibrous menisci even at 6 to 12 weeks after meniscectomy.

It is speculated that the application of delayed CPM promotes early focal fibrocartilagenous metaplasia of the fibrous meniscus following meniscectomy.

This study was carried out to assess the effect of bone marrow transplant into the 47 ununited fracture sites of the long bones of the extremities in 46 patients on bone healing. Among 46 cases, there were 43 pure fractures; a case of simultaneous ipsilateral femoral and tibial osteotomies for leg lengthening; a case of ununited repositioned cryo-treated proximal half of tibia as a limb salvage; and a case of internal transport of proximal tibia.

Among the 43 pure fractures, there were 11 hypertrophic, 30 oligotrophic, and 2 gap nonunions. Bone marrow transplant was performed for any type of the delayed union and nonunion, and was also indicated in the distraction callotasis site of poor osteogenesis.

Overall union rate in 43 fractures was 55.8% (24 cases). In two gap nonunions, no callus was formed. Union was obtained in all the 11 hypertrophic nonunions and 13 (46.4%) of the 30 oligotrophic nonunions. The oligotrophic and gap nonunions responded poorly to the marrow transplant. One of the two tibial osteotomy gaps healed with good evidence of endosteal callus formation. In a femoral osteotomy site for lengthening and in an ununited repositioned site of the cryo-treated tibia, there were no visible callus at all. The average time for clinical and radiological unions in the fracture cases were 5 and 7 months on average. In our series, there were no complications, including infection.

The results in this series suggest that bone marrow transplant is a good source of callus formation or stimulant in treating the delayed union and hyper- and oligotrophic nonunions of any origin, and also enhances the callus formation at the gap of the early stage of the internal transport.

The sagittal plane, which Pauwels regarded as being of no importance for the hip, was studied in the whole body with respect to posture while walking. After a preliminary study, which confirmed the importance of the sagittal plane for the hip, we performed a 3-dimensional modelling of the hip using the finite element method, with the aim of studying the resultant force exerted at the centre of the coxofemoral joint and of analysing the actions of the muscles from the efforts recorded. On the basis of these findings, we represented the overall mechanical problem of the hip in schematic terms as a variable dynamic balance. The results of this work also allowed us to establish in detail the impact of optimisation on the muscular actions and the impact of variations in displacement and the acceleration of the partial centre of gravity on the results recorded. Finally, the isolated hip model was developed, with the aims of allowing us to study the relations existing between variations in the angle of femoral anteversion and variations in forces, and of making a contribution to anthropological studies of the structures of locomotion through the ages.

No standard method has been provided to define the contact point of the tibiofemoral joint of the total knee prosthesis. Our objective was to estimate the contact point of the tibiofemoral joint in in vitro biomechanical testing of the total knee prosthesis. Three commercial knee prostheses were used for testing. We applied compression loads and used Fuji-prescale films to measure the contact areas at different flexion angles (0°, 10°, 30°, and 60°). The contact point was calculated when the maximum contact configuration was achieved. We used a sensitivity analysis and digital image analysis of the Fuji-prescale film to find the contact point at different flexion angles. From the results, we found that the contact points of the 3 prostheses were all approximately at 30%–60% of the depth of the tibial plateau dimension relative to the posterior edge and symmetrically relative to the midline of the mediolaterial width. All three prostheses had the same tendency in which the contact point first moved anteriorly during 0° to 10° flexion, and then moved more posteriorly after 10° flexion. The present method using the maximum contact area to estimate the contact point for different flexion angles, should be applicable for in vitro biomechanical evaluation of the total knee prosthesis.

The compressive and shear stiffness of periarticular osteophytes, hypertrophic femoral intercondylar notch and normal articular cartilage were compared by obtaining force-indentation curves and applying a shear force to the cartilage/bone interface. The primary stiffness (at 0–100N load) was similar for osteophytes (391N/mm), intercondylar notch (400N/mm) and normal articular cartilage (401N/mm). By contrast, the secondary stiffness (at 100–500N load) was much higher for the intercondylar notch (493N/mm) compared to the osteophytes (410N/mm). There were two varieties of osteophytes, "pink" and "white". Compared with "pink" osteophytes, "white" osteophytes exhibited features similar to a progressively hardening material and appear to be a more mechanically suitable material as an osteochondral graft for full thickness articular cartilage defect. The shear characteristics of all the samples were similar.

The relative contributions of the posterior elements on the human cervical spine behavior under axial compression and distraction were determined using the finite element modeling approach. This was accomplished by considering two structures: First, the intervertebral joint structure representing the anterior and posterior columns, including the C4–C6 vertebrae and the neighboring discs with the entire ligamentous complex; and second, the disc joint structure representing only the anterior column (vertebral bodies, discs and longitudinal ligaments). The anterior column sustained a higher share of the load than the posterior column under distraction. However, compression was shared equally among the anterior and the two posterior load bearing columns. The component internal stresses increased with posterior element removal. Consequently, inactivation or compromise in the posterior elements introduces additional internal loads or stresses in the anterior components which may accentuate degenerative changes or injure the cervical column. Thus, posterior complex integrity is critical for the load-carrying capacity of the cervical spine.