Study On The Anatomy Of The Proximal Phalanx-geal Medullary Canal And The Fracture Treatme-nt’s Exploration

Objective:The aim of our study was to find the narrowest section in the medullary canals and obtain the height of the narrowest section and medullary canals through X-ray film, CT scan and dissection of the proximal phalanx, to observe the medullary canal shape. So we can supply the anatomical basis for intramedullary fixation of the proximal phalangeal fractures and the parameters. We compared with the data among three groups, in order to search for the relationship among them, which is benefit for the surgery to evaluate the length and shape of the proximal medullary canal. On the basis of our research, we also suggest a new exploratory study on the proximal phalanx fracture.Methods:We collected30proximal phalangeal bones preserved in formalin which came from Tian Jin medical university between September2010and December2012as object of the research. The bones came from6hands of cadavers whose sex and age were not recorded which contain6thumb fingers,6index fingers,6middle fingers,6ring fingers and6little fingers. We only selected the proximal phalanx and dissected the soft tissues, and then numbered the proximal phalangeal bones respectively. Firstly, we used the X-ray to examine them.observing the proximal medullary canal shape, measuring the results with the vernier caliper consisting the length of the proximal phalangeal bone and medullary canals, the length from the narrowest section in the sagittal plane to the condyle, and the height of the narrowest section, so we could obtain the relative data; secondly, the proximal phalangeal bones had the CT scanning, and got the DICOM documents, so we could input them into the personal computer, then apply the Mimics software to reconstruct the shape of the proximal medullary canal and measure in the same above method on the sagittal and frontal planes; thirdly, we dissected the proximal phalangeal bones respectively and symmetrically along the central line of the proximal phalangeal bone, measuring the height of the narrowest section and the length from the narrowest section in the sagittal plane to the condyle, acquiring the relative data; finally, we used the SPSS 13.0software to analyze the data and to explore the relationship among the X-ray measurements,Mimics measurements and specimen’s measurements.Results:The mean lengths of the proximal phalangeal bone were the thumb finger37.16±5.59mm, the index finger39.80±1.55mm, the middle finger46.20±1.65mm, the ring finger42.03±1.73mm, the little finger31.87±1.02mm. The mean lengths of the proximal medullary canal were the thumb finger17.58±1.11mm, the index finger25.62±3.70mm, the middle finger26.37±3.71mm, the ring finger25.16±2.26mm, the little finger19.38±0.65mm. The ratio of the length from the narrowest section to the condyle and the length of the finger were specimen’s measurement0.3628±0.035, Mimics measurement0.3397±0.035and X-ray measurement0.3610±03038. The ratios of three groups were all normal distribution, comparisons among groups were tested by One-Way ANVOA analysis and LSD test, so the value P between specimen group and X-ray group was0.849, the value P between specimen group and Mimics group was0.016, the value P between X-ray group and Mimics group was0.026.Conclusion:We divided the medullary canals into four parts and they are head, narrow section, expansion and tail. The narrowest section is located the one third the the proximal phalangeal shaft through the X-ray film measurement, Mimics software measurement and specimen’s measurement, so it is of valuable reference for fixation in the medullary canal. The shape of medullary canal on the frontal plane was like Chinese characteristic "八", and the lateral plane was arch. The three-dimensional shape of medullary canal was taper. The ratio of height and width was less than1on any transverse cross-section. In the narrow section of medullary canal, the shaft walls thicker than the other parts, and the shaft walls were also thicker dorsally than palmarly. So it is feasibility to put the fixation in the medullary canal, and the fixation’s shape should be bar or taper to provide stable, because it can be across the narrow section to acquire the stabilization, or reaming the medullary canal is suited for fixing the fixation in the medullary canal to stabilize the fragments.