Jean-Michel Laffosse

Influence of Location, Fluid Flow Direction, and Tissue Maturity on the Macroscopic Permeability of Vertebral End Plates

Study Design. We implemented a pilot study in a growing animal model. The macroscopic permeability of the vertebral endplates was measured. The influence of location, tissue maturity, and fluid flow direction was quantified. Objective. We hypothesized that the macroscopic permeability of vertebral endplate may decrease with maturity of the vertebral segment. Summary of Background Data. The alternation of loading induced by the diurnal cycle generates convective flux into the vertebral segment with the dominant flow path through the vertebral endplates. The alteration of mass transport at the disc-vertebrae interface may interrupt the mechanobiologic balance, and have an effect such as degenerative changes or scoliosis. Methods. A previously validated method for measuring permeability, based on the relaxation pressure caused by a transient-flow rate was used. Three specimens were extracted from each L1 to L5 endplate. Seventy-one specimens were frozen, and 64 were stored fresh in a standard culture media. A microscopic analysis completed the biomechanical analysis. Results. At 2, 4, and 6 months, the mean permeability (10−14 m4/N · s, flow-in/flow-out) of the central zone was respectively: 1.23/1.66, 1.03/1.29, and 0.792/1.00. Laterally, it was 1.03/1.19, 1.094/1.001, and 0.765/0.863. For all groups, cartilage endplate and growth plate were both thinner in the center of the plate. Weak differences of the vascular network were detected, except for a small increase of vascular density in the central zone. Conclusion. The results from this animal study showed that the central zone of the vertebral endplate was more permeable than the periphery and the flow-out permeability was up to 35% greater than the flow-in permeability. Increase of permeability with decrease of cartilage thickness was noticed within the same age group. We also found a statistically significant decrease of the macroscopic permeability correlated with the tissue maturity.

Experimental study of an original radiographic view for diagnosis of cam-type anterior femoroacetabular impingement

PurposePrimary paraclinical investigation to look for femoral morphological abnormality consistent with cam-type anterior femoroacetabular impingement (FAI) must include specific radiographic projections of the hip from the following: cross-table, frog-leg or Dunn (90° and 45° flexion). We use a frog-leg type view with fixed angles as described by Chiron, obtained with the patient in a supine position, with the hip in 45° flexion-abduction and 30° external rotation. The X-ray beam is anteroposterior and centred on the femoral head. We evaluated this view by comparing it with other views in common use.MethodsIn this experimental study, we created artificial radio-opaque morphological abnormalities secured onto normal femoral necks. The femurs were placed in relation to a fixed pelvis using orthogonal landmarks, in the positions of the various radiographic views. The digital radiographs were analysed by two observers. Nineteen femurs were included to reveal a difference of 5° between the alpha angle of Nötzli et al. [11] measured on the Dunn view and the frog-leg 45/45/30 view (Student’s paired test).ResultsThe highest mean values of the alpha angle of Nötzli were always obtained with the frog-leg 45/45/30 view (87.4°, 86.2°, 84.5°) and the lowest with the cross-table view. We found a mean difference of 8.95° with the 90° Dunn view (P = 0.00007), 3.44° with the 45° Dunn view (P = 0.004) and 13.47° with the cross-table view (P = 0.002).ConclusionsThis experimental study confirmed the value of the frog-leg 45/45/30 view in assisting diagnosis of cam-type FAI.

Osteoblast-derived sphingosine 1-phosphate to induce proliferation and confer resistance to therapeutics to bone metastasis-derived prostate cancer cells

Sphingosine 1‐phosphate (S1P) plays important roles in cell proliferation, differentiation or survival mainly through its surface G‐protein‐coupled receptors S1P1−5. Bone represents the major site of metastasis for prostate cancer (CaP) cells, which rely on bone‐derived factors to support their proliferation and resistance to therapeutics.

Correlations between effective permeability and marrow contact channels surface of vertebral endplates

Homeostasis of the intervertebral disc relies on nutrient supply and waste clearance through the dense capillary network that is in contact with the cartilage endplate (CEP). We developed a micro‐computerized tomography (micro‐CT) method to quantify the marrow contact channel surface (MCCS) with the CEP and to validate the hypothesis according to which MCCS was correlated to the effective permeability of the vertebral endplate (VEP) and influenced by the mechanical stimuli. The influence of compression loading on local vascularization was investigated. Six 4‐week‐old skeletally immature pigs were instrumented with left pedicle screws and rod at both T5–T6 and L1–L2 levels to create asymmetrical spine tethers. After 3 months of growth, three cylindrical specimens of the VEP (one central and two lateral right and left) were obtained from both the instrumented and the control levels. We used a previously validated method for measuring permeability. Micro‐CT analysis (resolution 12 µm) yielded a gray‐scale 2D‐image of the discal end of each specimen converted into a binary 2D‐image to derive the MCCS. Correlations between MCCS and effective permeability were assessed. Effective permeability and MCCS were significantly decreased compared to the control group especially on the tethered side (−41.5%, p = 0.004 and −52.5%, p = 0.0009, respectively). Correlations were significant and showed maximal value (r2 = 0.430, p < 0.0001) on the tethered side involving maximal compressive loadings. Mechanical stimuli, due to unbalanced growth, altered the vascularization and the convective properties of the CEP. The cascade of mechanobiological events should offer perspectives for research on disc degeneration and attempted treatment.

Anterolateral mini-invasive versus posterior mini-invasive approach for primary total hip replacement. Comparison of exposure and implant positioning

IntroductionWe conducted a prospective study to compare the exposure and implant positioning in primary total hip replacement through the anterolateral minimally invasive (ALMI) approach versus the posterior minimally invasive (PMI) approach.Materials and methodsWe applied these techniques to 2 consecutive groups (33 and 43 patients, respectively) comparable preoperatively. All the patients received the same cementless stem and acetabular component.ResultsThere were neither significant difference in femoral or acetabular component positioning nor in limb-length discrepancy. Acetabular exposure was easy through the ALMI approach. Femoral exposure was more difficult as fractures of the trochanter and femoral perforation in our study show.ConclusionFor us, exposure and implant positioning through the ALMI approach and the PMI approach are comparable and reliable. However, we recommend caution during the initial learning curve in osteoporotic patients due to the higher rate of peroperative complications for the ALMI approach.

The anconeus, an active lateral ligament of the elbow: new anatomical arguments

PurposeAs there are a few detailed anatomical studies of the active function of anconeus muscle in stabilizing the elbow, we aimed to look for anatomical features confirming its role as an active stabilizer of the humero-ulnar joint.MethodsThirty fresh unembalmed elbows from 15 cadavers were dissected. We examined the anatomy, insertions, relationships and orientation of the muscle fibres of the anconeus.ResultsThe anconeus lies in a separate compartment from the other forearm muscles, but in continuity with the extensor (triceps) compartment of the arm. In all the cases, at its proximal extremity we observed continuity of muscle and tendon with the vastus lateralis of the triceps brachii. The muscle fibres run downward and backward, parallel to the fibres of vastus lateralis of the triceps, when the elbow is in extension. Its deep aspect adheres closely to the lateral joint capsule of the humero-ulnar joint.ConclusionThe new anatomical characteristics of the anconeus revealed in this study make this muscle a digastric head of triceps brachii that coapts the ulna to the humerus and so reduces varus instability. The close relationships between triceps brachii and the anconeus on one hand and between the joint capsule and the anconeus on the other make the latter muscle an active lateral stabilizer of the elbow.

Mouse model of fracture pain.

Background:The aim of this study was to validate a model of postfracture pain in mice, which was evaluated in the presence and the absence of morphine and ketoprofen. Methods:The study was divided into two parts: protocol A, the effects of closed fracture; and protocol B, the effects of morphine and ketoprofen on fracture pain. In protocol A, mice were assigned to three groups: group 1, sham incision; group 2, sham pinning; or group 3, fracture. In protocol B, mice were randomly assigned to four groups to receive morphine (3 or 10 mg/kg body weight), ketoprofen (50 mg/kg body weight), or placebo (vehicle). Three tests were used to assess pain behavior: von Frey filament application, hot plate test, and a subjective pain scale. Results:In protocol A, thermal nociception, mechanical nociception, and subjective pain were significantly modified in group 3 (fractured) compared with control groups 1 and 2 (sham groups). In protocol B, when tests were repeated for 240 min in morphine-treated animals and in ketoprofen-treated animals, reduction of mechanical nociception, thermal nociception, and subjective pain scale score were observed. Morphine and ketoprofen administration provided the same effect on behavioral testing on postoperative days 1 and 2. Conclusion:This mouse model seems to be a reliable and reproducible tool to investigate the effect of closed bone fracture on several parameters, such as pain, remodeling, and recovery. Moreover, it allows studying the effects of various pharmacologic treatments as well as the involvement of various systems using different genetically modified strains of mice.

Anatomy of the bands of the hamstring tendon: How can we improve harvest quality?

BACKGROUND The hamstring tendons, gracilis and semitendinosus are widely used in ligament and reconstructive surgery. Their accessory bands or insertions are technical pitfalls during harvesting. METHODS Thirty fresh cadaver knees have been studied, in order to 1) determine the anatomy of the bands of the gracilis and semitendinosus tendons, and, 2) to identify risk factors for failure during harvesting. RESULTS Semitendinosus always had at least one band, sometimes two, strong, tendinous, and generally running to the fascia of gastrocnemius medialis to which they are attached, at an acute angle in a distal direction. Their presence is constant and they are only exceptionally found more than 100 mm from the tendons tibial insertion. Gracilis shows the greatest anatomical variability, and over one quarter have no bands (although there may be as many as three). Their location, destination and angle of attachment to the tendon vary greatly. These bands are mainly aponeurotic and less strong, but must be carefully and widely dissected. CONCLUSION Anatomical variability makes harvesting of pes anserinus tendons difficult. Three simple anatomical criteria have been highlighted that can be assessed by the surgeon during harvesting. The criteria are the insertion, the direction and the anatomical type of the bands.

Obesity is no longer a risk factor for dislocation after total hip arthroplasty with a double-mobility cup

PurposeDislocation is one of the most feared complications after total hip arthroplasty (THA). This risk is greater in obese patients compared with the general population.MethodsWe performed a retrospective cohort study in which the main objective was to compare the dislocation rate between obese patients (BMI > 30 kg/m²) (exposed group) and non-obese patients (BMI ≤ 30 kg/m²) (unexposed group) after primary THA with a double-mobility acetabular cup. The patients had a minimum follow-up of 24 months.ResultsThe ‘obese’ group consisted of 77 THA cases and the ‘non-obese’ group of 425 cases; the two groups were similar in terms of age, gender and ASA score. After a mean follow-up of 58.3 ± 27 months (range 27–159), 43 patients had been lost to follow-up and 56 had died; the two groups had similar mean values. One patient in the ‘obese’ group had suffered a dislocation due to a fall 16 months after the THA. One patient in the ‘non-obese’ group had suffered a dislocation after a periprosthetic femur fracture with stem subsidence two months after the THA procedure. Both patients underwent surgical revision where the double-mobility cup was preserved; there were no further dislocation events as of the last follow-up. The dislocation rate in the two groups was similar (1.3 % versus 0.23 %, p > 0.05). No cases of loosening were found. Revisions were secondary to deep or superficial infection (n = 22), periprosthetic femur fracture (n = 10) or haematoma (n = 3).ConclusionThese findings imply that double-mobility cups are a reliable way of reducing the risk of dislocation in obese patients after primary THA.

Shelf arthroplasty by minimal invasive surgery: technique and results of 76 cases

Shelf arthroplasty is an old technique which by a classical approach, proposed by Lance in 1925, had a low morbidity rate and long term known results. A minimal invasive approach reduces the magnitude of the operation, its consequences and might allow one to broaden its indications. The approach is 4 cm long at the anterolateral part of the hip, through the space between tensor fascia latae and gluteus muscles. A 3x3 cm cortical-cancellous autograft is applied using a guide wire positioned by fluoroscopy and the osteosynthesis is based on a cannulated screw. 76 cases were reviewed over two years (4.6 years average, 2-8 years). The average hospitalization period lasted for three days; patients have to respect partial weight bearing for two months and no one has been placed in a re-education center. 75% patients had a completely painless hip without limiting their activity. 93% shelves are consolidated with a callus in three months; 6% nonunion was due, in part, to a technical mistake. No infection, no phlebitis, no palsy of the cutaneo lateral nerve has been evidenced.