A biomechanical cadaveric study of a modified U-shaped interspinous distraction device.

STUDY DESIGN: An experimental study. OBJECTIVE: To analyze the effects of a modified U-shape interspinous distraction device (IDD) on the stability of a destabilized lumbar spine model. SUMMARY OF BACKGROUND DATA: The use of IDD for treatment of lumbar spine pathology remains a subject of debate. A modified design of an IDD consisted of a titanium (Ti) U-shape dynamic stabilizer and a Ti tensioning wire loop was biomechanically tested. MATERIALS AND METHODS: Six sets of cadaveric lumbar vertebrae levels 1-5 (L1-L5) were subjected to loads in flexion, extension, and lateral bending in the 4 following sequences: intact specimen, unilateral facetectomy and discectomy at L3-L4, insertion of the modified U-shape IDD at L3-L4, and pedicle screw fixation at L3-L4. The range of motion (ROM) of L3-L4 following modified U-shape IDD insertion was compared with that of the intact specimen. The ROM of the adjacent vertebrae (L2-L3 and L4-L5) following modified U-shape IDD insertion was compared with that after pedicle screw fixation. Statistical analysis was performed using the Wilcoxon signed-rank test. RESULTS: The modified U-shape IDD decreased the ROM of a destabilized L3-L4 in all testing load (P<0.05). The stability of L3-L4 following the modified U-shape IDD insertion was restored to that of the intact specimen (P>0.05). The ROM at adjacent vertebrae after the modified U-shape IDD placement was similar to the ROM obtained after pedicle screw fixation at L3-L4. CONCLUSIONS: The modified version of a U-shape IDD is effective in stabilizing an unstable segment of the lumbar spine. The device does not create deleterious effects on the adjacent vertebrae.

Anthropometric measurements of knee joints in Thai population: correlation to the sizing of current knee prostheses.

Anthropometric data on the distal femoral condyle and the proximal tibia of 200 knees in 200 Thai subjects were measured using magnetic resonance imaging (MRI). The data including the resected femoral anterior-posterior (AP) length, the resected femoral medial-lateral (ML) width, the resected tibial AP length and the resected tibial ML width were measured. A characterization of the aspect ratio (the ML to AP dimensions) was made for the distal part of the femur and the aspect ratio (the AP to ML dimensions) was made for the proximal part of the tibia. All parameters were compared to the size of the total knee prosthesis with four prosthetic systems which currently used in Thailand: NexGen (Zimmer), P.F.C. Sigma (Depuy-Johnson & Johnson), Genesis II (Smith & nephew), and Scorpio (Stryker). The results of this study could provide fundamental data for the design of knee prostheses suitable for the Thai population.

Progressive quadriceps incision during minimally invasive surgery for total knee arthroplasty: the effect on early postoperative ambulation.

A prospective series of 114 consecutive minimally invasive surgeries for total knee arthroplasty was performed using the quadriceps-sparing approach at the beginning. Intraoperatively, when the knee was in 45 degrees to 60 degrees of flexion, lateral patella subluxation was evaluated. A progressive quadriceps tendon incision with a 1-cm increment was applied if the patella could not be completely slid. The mean follow-up time was 24 months. There were 3 groups according to the length of quadriceps incision: group A (17 knees) had no or 1-cm quadriceps incision; group B (60 knees) had 2-cm incision; and group C (37 knees) had 3-cm incision. The average operative time, blood loss, pain score, preoperative range of motion and postoperative range of motion at 2 weeks, 6 weeks, 12 weeks, and 3 months were not significantly different among groups. Patient ability for early ambulation (sitting, knee straightening, standing, and walking) was indifferent between groups A and B; however, this was significantly delayed in group C. In conclusion, minimally invasive surgery for total knee arthroplasty with 2-cm quadriceps incision or strict quadriceps-sparing approach provided no difference on early ambulation.

Results of the 136 consecutive minimally invasive total knee arthroplasties.

The authors evaluated results of 136 consecutive minimally invasive total knee arthroplasties (MIS TKAs). The first 22 knees, performed with strict patient selection criteria, were determined as a learning experience. According to results of the next 114 knees, the average wound length was 9.2 centimeters and the average blood loss was 470 milliliters. At a mean follow-up of 14 months, the mean Knee Society score improved from 37.5 to 96 points with 96.3% of excellent results. Sixty-five knees, group A, had within 10 degrees of varus and 49 knees, group B, had more deformity. Clinical results of both groups were not statistically different in terms of operative time, blood loss, pain score, postoperative knee flexion at 2 weeks and 6 months and postoperative day of walking. However, the ability to straighten the knee was significantly delayed in knees with more deformity (group B). After gaining learning curve, surgeons could extend performing MIS TKA in patients with more knee deformity.

Comparison of tissue reaction and osteointegration of metal implants between hydroxyapatite/Ti alloy coat: an animal experimental study.

BACKGROUND: One important clinical application of hydroxyapatite (HA) is coating on metal implants to stimulate osteo-integration thus enhancing fixation of the implant to bone, especially plasma-sprayed HA coating applied on Ti alloy substrate. The poor bonding strength between HA and Ti alloy has been of great concern to orthopedists. The biocomptable coat such as Ti alloy (TiO2) coat is one method to improve adhesive strength. OBJECTIVE: The objective of this study was to detect and analyze possible differences in bone formation, bone integration and tissue reaction between group I (uncoated Titanium), group II (Hydroxyapatite coated Titanium), and group III (Hydroxyapatite/TiO2 coated Titanium) implant specimens when embedded into bony hosts. METHOD: Rectangular specimens were implanted into the femoral bone of adult dogs in randomly different sites including: proximal left, proximal right, distal left, distal right. The tailor-made implant specimens were inserted in 5 x 5 mm preprepared sockets. Radiographic evaluation was taken at 0, 1, 3 and 6 months. All animals were sacrificed at 3 and 6 months post implantation. The femoral bone containing implants were dissected and then prepared to be further investigated. The bone-implant interface was analyzed by H&E surface staining, radiography and scanning electron microscopy. Data concerning percentage of osteointegration and adhesiveness of hydroxyapatite layer from different kinds of implants along the entire length of each implants were collected and analyzed for evaluation of any significant differences. RESULTS: No osteo-integration was noted in Group I, but there was 25.57 per cent osteointegration in Group II and 28.63 per cent in Group III. No statistically significant differences were observed between Group II and Group III. However, the coating layer in Group II was found to have detached, in some area, from the metal substrate. Histologically, no adverse tissue reaction was found around any kind of implant. CONCLUSION: Biocompatable bond coat is one of the methods to improve adhesive strength of hydroxyapatite coated implants. In the present study it could be concluded that, besides the improvement in adhesiveness, the intervening TiO2 coating layer had no negative effect concerning bone formation and integration and also showed no adverse surrounding soft tissue reaction.

The remained patellar tendon strength after central one third removal : a biomechanical study.

The study was aimed at comparing the ultimate load bearing capabilities between normal patellar tendons (control group) and tendons after central one-third removal (removal group). Eleven fresh Thai cadavers provided study specimens. The average age of the cadavers was 24.86 +/- 7.13 years. Five tendons were used as control specimens and another six tendons underwent central one-third removal. The Instron 5583 testing machine and Cooper's technique of measurements were used to test the ultimate load. Rate of elongation of tendon was set at 500 mm/sec. The results showed that the removal group cross-sectional area was 48.67 mm2 or 49.64 per cent of the control group (98.04 mm2). The mean ultimate load of the control group was 4,365.59 N. The mean ultimate load of the removal group was 2,226.58 N or about 51 per cent. The energy level to breaking point in the control group was 72.17 J and 32.58 (45.14%) in the removal group. The average width of the central one-third portion was measured at 8.68 +/- 0.56 cm. Generally in a clinical situation, when the ultimate load is reduced to about half in the donor knee, care must be taken before allowing full weight to bear. Caution should also be emphasized in cases where a routinely 10 mm wide graft has been taken, as the donor tendon may be weakened by more than half and may rupture prematurely.

A capsular dilatation facilitated shoulder manipulation for treating patients with frozen shoulder.

Forty patients with a diagnosis of frozen shoulder who had symptom for an average of 8 months and failed conservative treatment of at least 6 weeks of physical therapy were treated with capsular dilatation facilitated shoulder manipulation. Post-manipulation, the patient underwent arthroscopy for visualization, fibrin debridement and bleeding point coagulation. All the essential intra-articular structures ie, glenohumeral ligament, rotator cuff were intact. Post-operatively, all patients revealed substantial gain in shoulder range of motion as well as diminished shoulder pain. The average flexion, abduction, and internal rotation gain were 76.9+/-8.9, 18.1+/-5.7, 9.6+/-7.1 degrees respectively. External rotation gain in the position of 90 degrees shoulder abduction and shoulder adduction were 53.0+/-9.97 and 31.4+/-7.2 degrees respectively. The average pain score by visual analogue scale pre and 6-month post-manipulation were 80.6+/-8.6 and 7.6+/-7.3 respectively with the average of pain score of 73.0+/-10.4. The authors proposed an effective and safe technique employing intra-articular pressure to facilitate shoulder manipulation in order to treat frozen shoulder.