Combination of Heel-strike like Mechanical Loading with Deproteinized Cancellous Bone Scaffold Implantation to Repair Segmental Bone Defects in Rabbits.

Under physiological conditions bone defects often occur at mechanical load bearing sites and bone substitutes used for regeneration should be similarly subjected to mechanical loading stress. In this study, we investigated whether a novel heel-strike like mechanical loading method can be used as a complementary therapy to promote bone regeneration following bone substitute grafting. To test this, three groups of rabbits with segmental bone defects in the tibia were implanted with bovine deproteinized cancellous bone scaffold (DCBS), with one group also receiving heel-strike like mechanical loading generated by a rap stress stimulator. From weeks 4-12 post-operation X-ray and micro-CT scanning showed that rabbits receiving combination therapy had significantly more callus at the bone defect. Moreover, bone defects in the combination group were completely replaced with new bone at week 12, while the DCBS implantation alone group healed only partially and rabbits receiving neither DCBS nor mechanical loading developed only small calluses throughout the observation period. Analysis of micro-CT scanning results demonstrated that new bone density in the combination group was significantly higher than the DCBS only group at weeks 4 and 12 (p<0.05). H&E staining results also indicated a significantly higher percentage of new bone in the bone defect area and a lower percentage of residual scaffold in the combination group compared to the DCBS only group (p<0.05). Thus, this heel-strike like mechanical loading method appears to accelerate bone regeneration following substitute implantation by restoring a local mechanical loading environment in segmental bone defects.

Usefulness of calf circumference as a measure for screening low birth weight infants.

Usefulness of calf circumference (CC) for screening low birth weight (LBW) was assessed in comparison with other anthropometric measurements, crown heel and crown rump lengths (CHL, CRL), Chest (Ch C), head (HC) and arm (AC) circumferences in 256 infants within 24 hours of birth. Calf circumference showed highest degree of correlation (r = 0.83) with birth weight followed by arm and chest circumference and crown heel length. Step down multiple linear regression analysis of birth weight showed highest R2 value with combination of calf, arm and crown heel length (82.1%). Addition of other measurements did not improve the predictive value of the model. Sensitivity of these parameters in screening LBW infants (less than 2500 g) showed 95.7% critical limit for calf followed by 82.6% with arm circumference and 72.5% with crown heel length. False positive responses were similar (18-20%) with all the three parameters. Calf circumference being highly sensitive and easy to measure, is useful in screening most of the low birth weight infants in the communities where weighing scales are not available or cannot be used by peripheral workers.