ABSTRACT
<p><b>OBJECTIVE</b>To compare clinical effects between Pavlik harness and Bryant traction in treating femoral shaft fractures in infants,including the time of hospitalization, expense of treatment, complications,time of bone union.</p><p><b>METHODS</b>From May 2005 to August 2010,the clinical data of 42 infants with femoral shaft fractures were retrospectively analyzed. Among the patients, 23 cases were treated with Pavlik harness(Pavlik harness group),there were 14 males and 9 females,ranging in age from 1 to 12 months with an average of (5.5+/-2.4) months,including upper 1/3 segment of 16 cases and middle segment of 7 cases; transverse fracture of 18 cases and oblique fracture of 5 cases. The other 19 patients were treated with Bryant traction (Bryant traction group),there were 15 males and 4 females,ranging in age from 2 to 12 months with an average of (6.7+/-2.8) months,including upper 1/3 segment of 13 cases and middle segment of 6 cases;transverse fracture of 12 cases and oblique fracture of 7 cases. The time of hospitalization,expense of treatment,complications,time of bone union were analyzed in the patients.</p><p><b>RESULTS</b>All patients were followed up with an average of 25.3 months (ranging from 19 to 30) in Pavlik harness group and 23.7 months (ranging from 17 to 28) in Bryant traction group. Time of hospitalization, expense of treatment in Pavlik harness group were respectively (0.4+/-0.7) d, (2147.7+/-64.9) yuan; and in Bryant traction group were respectively(27.1+/-2.2) d, (2741.3+/-227.6) yuan;there was significant difference between two groups(P<0.05). No complication was found in Pavlik harness group and 8 cases complicated with skin hydroa in Bryant traction group, there was significant difference between two groups (P<0.05). Time of bone union,difference of both lower extremities in Pavlik harness group were respectively (4.1+/-0.3)weeks, (6.3+/-4.1) mm;and in Bryant traction group were respectively (3.9+/-0.3) weeks, (7.6 +/-4.3) mm; 20 cases got bone healing in Pavlik harness group and 18 cases got bone healing in Bryant traction group;there was no significant difference between two groups (P>0.05).</p><p><b>CONCLUSION</b>Compared with Bryant traction method,Pavlik harness method has obvious advantages in time of hospitalization, expense of treatment, complications in treating femoral shaft fractures in infants.</p>
Subject(s)
Female , Humans , Infant , Male , Femoral Fractures , Therapeutics , Orthotic Devices , Traction , MethodsABSTRACT
Objective To investigate the biomechanical stability of both DHS (dynamic hip screw) and PFN (proximal femoral nail) for treating unstable intertrochanteric fractures. Methods A standard 4-part osteotomy was performed in 8 pairs of fresh frozen human cadaver femurs, which were then randomly assigned to two groups: PFN group and DHS group for biomechanical testing. These specimens were applied to a cyclic load up to 200, 400, 600, 800, 1 000, 1 200, 1 400 N, respectively. Fracture displacement was measured during the loading to determine biomechanical stability of the implant. Each specimen was repeatedly loaded for 5 times to calculate the average displacement and draw the load-displacement curve. For failure testing, the initial load and loading rate was set at 1 400 N and 10 N/s, respectively. The applied compressive load was increased by 600 N each time for five cycles. The pressure was gradually increased to its peak force, and sustained for 10 second before it was gradually decreased to 0 N. The highest force value sustained before failure was defined as the maximum strength of the implant. Results The biomechanical testing on all specimens was completed successfully. There was no damage to the internal fixation. The average displacement and stiffness in DHS group were (3.92±2.21) mm and (215.28±58) N/mm, while those in PFN group were (4.22±1.80) mm and (197.06±34.20) N/mm, so no significant difference was found between the DHS and the PFN group (P> 0.05). New fracture occurred at the distal end of nail in PFN group. The DHS was fractured at the distal cortical screw, but no nail was cut out of the femoral head. The average load required for failure was (4 312±560) N in PFN group and (3 954±520) N in DHS group, and no significant difference was found between the two groups(P＞0.05). Conclusions The test shows that the PFN does not appear to offer any distinct biomechanical advantage over the DHS in the treatment of unstable intertrochanteric fractures. The implant chosen for treating intertrochanteric fractures must depend on patient’s fracture geometry, and anatomic reduction should be conducted in clinical treatment. If the anatomic reduction is difficult, trying to recover continuity of the posterior cortical bone would be necessary.
ABSTRACT
<p><b>OBJECTIVE</b>To study the anatomical and biomechanical features of the interosseous membrane (IOM) of the cadaveric forearm.</p><p><b>METHODS</b>Ten radius-IOM-ulna structures were harvested from fresh-frozen cadavers to measure the length, width and thickness of the tendinous portion of IOM. Then, the tendinous portion was isolated along with the ulnar and radial ends to which the tendon attached after measurement. The proximal portion of the radius and the distal portion of the ulna were embedded and fixed in the dental base acrylic resin powder. The embedded specimen was clamped and fixed by the MTS 858 test machine using a 10 000 N load cell for the entire tensile test. IOM was stretched at a speed of 50 mm/min until it was ruptured. The load-displacement curve was depicted with a computer and the maximum load and stiffness were recorded at the same time.</p><p><b>RESULTS</b>The IOM of the forearm was composed of three portions: central tendinous tissue, membranous tissue and dorsal affiliated oblique cord. IOM was stretched at a neutral position, and flexed at pronation and supination positions. The tendinous portion of IOM was lacerated in 6 specimens when the point of the maximum load reached to 1021.50 N+/-250.13 N, the stiffness to 138.24 N/m+/-24.29 N/m, and the length of stretch to 9.77 mm+/-1.77 mm. Fracture occurred at the fixed end of the ulna before laceration of the tendinous portion in 4 specimens when the maximum load was 744.40 N+/-109.85 N, the stiffness was 151.17 N/m+/-30.68 N/m, and the length of the stretch was 6.51 mm+/-0.51 mm.</p><p><b>CONCLUSIONS</b>The IOM of the forearm is a structure having ligamentous characteristics between the radius and the ulna. It is very important for maintenance of the longitudinal stability of the forearm. The anatomical and biomechanical data can be used as an objective criterion for evaluating the reconstructive method of IOM of the forearm.</p>