The Biomechanics And Clinical Study Of Injury On The Heel Fat Pad

BackgroundFoot is the furthest structure of human limbs.Its main function is to bear weight and walking.It is the most important and direct weight-bearing and walking organs of human body.Foot transfers our weight to the ground,balances our posture and helps walking.During the gait cycle,the heel is the first contaction point between the body and the ground,bearing 80%of the body’s weigh.It is the main absorber of the ground reaction.The anatomical structures of heel mainly include calcaneus,plantar aponeurosis,heel fat pad,skin and blood vessels and nerves surrounding them.The heel fat pad has the function of supporting and buffering.It can absorb the shock to the human body.Once the anatomical structures of the heel pad are damaged,the function of weightbearing and walking will be seriously affected and the quality of work and life will be seriously damaged.In recent years,there have been many basic and clinical studies on calcaneus and blood vessels and nerves at home and abroad,but there are few specialized studies on the heel fat pads.The anatomical structure and function of heel fat pad is unique.The heel fat pad is formed by the fibers perpendicular which connects the heel skin with the surface of the calcaneus,separates and wraps the adipose tissue.It can prevent sliding and absorb shock.Once the heel fat pad degenerates and damages,it will affect the function of weight-bearing and walking,seriously damage the quality of work and life In view of the lack of research and reports on this tissue at home and abroad,we attempt to study the biomechanics of heel fat pad,the relationship between the heel fat pad and painful heel syndrome,the changes of heel fat pad after calcaneal fracture and the clinical treatment after acute open injury.The study was carried out in the following four sections:The first part:The study of heel fat pad biomechanics in normal adultsObjective:To investigate the pressure on the heel fat pad in normal adults in different states,and to analyze the influence of age,sex,weight to the heel biomechanics,so as to explore the relationship between the physiological and pathological changes of heel fat pad according to gender、age and body mass index.To provide mechanical data for the further study of heel fat pad and guide for repairation and rehabilitation to the heel fat pad.Methods:80 healthy adult volunteers were selected from the medical staff and interns to participate the study.There were 40 males and 40 females,aged 20-60 years,The name,gender and age were recorded in detail.They were divided into four groups according to age and two groups according to sex.According to the body mass index,they were divided into three groups.Static and dynamic heel pressure parameters were measured by Footscan insole.Then to Compare these pressure parametersResult:1.Distribution of pressure on the heel fat pad in adults(Kpa)The heel(heel fat pad)is the most important part of weight-bearing under static conditions.There is no statistical significance between the maximum pressure on the left and right heelThe average maximum peak pressure on the heel(heel fat pad)is higher.There is no statistical significance between the average maximum peak pressure on the left and right heel.2.The influence of gender to the pressure distribution on the heel fat padThere is significant difference in the pressure distribution on heel fat pad between men and women at rest or during natural walking.3.The influence of age to the pressure distribution on the heel fat padThe maximum pressure on the heel fat pad decreases with age,there is no significant difference between the four groups.4.The influence of body mass index to the pressure distribution on the heel fat padThe maximum heel pressure and the maximum peak pressure of heel increased with BMI and there is statistically significant difference among the three groups.Conclusion:The heel(heel fat pad)is the most important part of weight-bearing under static conditions.When walking normally,the pressure on heel fat pad increases significantly.However,the heel is still the place where the pressure is greater.There is no statistical significance between the pressure on the left and right heel fat pad.There is significant gender difference in pressure on heel fat pad.The pressure on heel fat pad decreases with age,there is no signi ficant difference among age groups.The pressure on heel fat pad is positively correlated with body mass index.The second part:An experimental study on the relationship between the heel fat pad and painful heel syndrome,Objective:To explore the relationship among thickness of the heel fat pad,elasticity and painful heel syndrome to the middle-aged and elderly by measuring the thickness of heel fat pad in unilateral painful heel and normal contralateral foot.Methods:60 patients with unilateral heel pain were randomly selected from our outpatient department,including 30 males and 30 females.The thickness of heel fat pad was measured by ultrasonic probe.The compression coefficient of heel fat pad was calculated and analyzed according to gender、age and body mass index.Results:Under non-load condition,the thickness of heel fat pad in heathy foot was as follows:male,14.76± 1.57;female,13.52± 1.54.Underload condition,respectively 5.25± 1.38 and 4.14±1.35,and the compression coefficients was as follows:0.36±0.10 and 0.31 ±0.09,respectively.Under non-load condition,the thickness of heel fat pad in heathy foot was as follows:<40 years old,14.13±2.09;>40 years old,13.01±1.98.Under load condition,respectively 4.87±2.03 and 5.01±1.92,and the compression coefficients was as follows:0.34±0.09 and 0.38±0.08 respectively.Under non-load condition,the thickness(mm)of heel fat pad in heathy foot was as follows:normal weight,14.01±2.03;overweight,15.15±2.0.Under load con dition,respectively 4.76±2.01 and 5.86±1.98,and the compression coefficients was as follows:0.34±0.08 and 0.38±0.04 respectively.Under non-load condition,the thickness(mm)of heel fat pad in painful heel was as follows:male,15.75±1.53;female,14.51±1.53.Under load condition,respe ctively 5.96±1.34 and 4.86± 1.34,and the compression coefficients was as follows:0.38±0.14 and 0.33±0.04 respectively.Conclusion:The thickness of heel fat pad decreases with age,thickens in male and in obese people.The critical values measured byB-mode ultrasonography for men and women were respectively 15mm and 14mm.Pathological changes can be predicted and evaluated by measuring the thickness of heel fat pad.The Third part:The Changes of heel fat pad after calcaneal fractureObjective:To study the changes of heel fat pad after calcaneal fracture by magnetic resonance imaging and to explore the correlation between the chronic heel pain and the heel fat pad after calcaneal fracture.Methods:Thirty patients with calcaneal fracture who were treated surgically in our hospital were selected for the study.The thickness of heel fat pad was measured by magnetic resonance technology before and after operation,and the changes of heel fat pad in magnetic resonance image were discussed.Result:There were obvious signal changes in the soft tissue around the injured calcaneus during the acute phase.There was significant difference between the two sides(T=7.74,P<0.001).No signal changes were detected in the injured heel after one year.There was no significant difference between the two sides(T=0.31,P>0.05).Conclusion:There was not obvious damage to the overall structure in the heel fat pad with calcaneal fracture.There is no significant correlation between the chronic pain and the heel fat pad after calcaneal fracture.The Fourth part:Reduction and Anchorage with Compressed Fixation for Treating the Acute Injury of Heel Fat PadObjective:Due to the paucityof literature on treating the acute open injury of heel fat pad,we described our initial experience treating acute open injury of the heel fat pad to determine the ideal treatment method.Methods:A total of 53 patients with the acute open injury of heel fat pad admitted to our hospital were selected for the study and were randomly divided into 2 groups:Reduction and Anchorage with Compressed Fixation group and the only reimplanted and sewn group.Twenty-seven of the heel fat pads were compressed and fixed using a flat,hard piece of plastic and hollow screws;The other 27 were only sewn without tension.The clinical results were evaluated according to the American Orthopedic Foot and Ankle Society hindfoot score(A OFS)and the British Medical Research Council function evaluation criteria.Results:In Reduction and Anchorage with Compressed Fixation group,flaps of 12 feet with retrograde avulsion injury survived successfully.Partial flap necrosis occurred in 8 feet.All flap necrosis occurred in 7 feet.Results were excellent or good for 74%of patients according to the the the British Medical Research Council.However,in the only reimplanted and sewn group,results were ex cellent or good for 44%of patients according to the the British Medical Research Council.Conclusions:Reduction and Anchorage with Compressed Fixation is effective for treating the acute open injury of heel fat pad,with high success rates and good utility.