First, the importance of accepting the cavity: accepting the cavity is the main component of a prosthetic limb, which is the link between human and technology 1, first of all, it must be stressed that the prosthetic accepting cavity is the most important component between the human body and prosthetic parts, it must be installed to help the patient to control his prosthesis. 2, we help the patient to control his prosthesis as well as possible, first of all, the residual limb must be well accommodated, so that it will not produce a peak in a certain part, a certain area when absorbing and transmitting the body’s gravity, the transmission of gravity is more evenly distributed, feel more comfortable, the patient will feel at ease at any time, feel in control of his prosthesis when moving. 3. Discuss with the patient about the concept of sciatic inclusion, and the procedures for measuring and taking the type, and obtain the patient’s approval of the operation to be performed and the reasons for it. Even in a seasoned amputee, the taking of a sciatic inclusion cavity requires more effort and time than a quadrilateral cavity. Patient acceptance of the advantages and disadvantages of the sciatic inclusive receptive cavity is very important. It is important to explain and inform the patient of technical details such as which anatomical structures need to be accommodated in the receiving cavity, especially the areas on the pelvis that need to be touched and measured. Use the pelvis and the receiving cavity, the model, and visualize these terms in front of the patient. For those patients who know the medical terminology, provide them with some articles on hand to read about the sciatic accommodating receptive cavity. In this way, your patients will appreciate your efforts to persevere in order to solve the various problems encountered in the initial adaptation of the receptive cavity. 4. Use familiar technical methods to measure the range of motion of the hip joint to ensure accurate determination of the hip flexion contracture angle, which is the basis for determining the initial flexion angle of the target receiving cavity later. If the residual hip joint can actively extend and is close to normal, the initial flexion angle is set between 0°-3°; otherwise, if there is flexion contracture, the initial flexion angle of the receiving cavity is the contracture angle plus 3°-5° of flexion angle. Special attention should be paid to the measurement of hip extensor strength using standard procedures, such as the Oxford Manipulation muscle strength test. 5. Measurement of hip adduction range of motion and strength: Measure the hip adduction range of motion of the residual limb, and if there is no contracture, use a technique you are familiar with to measure and record the angle of adduction/abduction of the femoral stem on the healthy side relative to the vertical line. Make sure the pelvis is level when measuring in the standing position. The average angle of adduction is 9°-11° for men and 11°-13° for women. If contracture is present, record the angle of adduction of the femoral stem of the residual limb as close to the “normal” angle of adduction as possible. 6. Measurement of residual limb tissue density: The residual limb is placed between the hands to determine the residual limb tissue density. The patient is asked to contract the residual limb muscles and rotate the soft tissue over the residual limb muscles. Tissue density can usually be described as “tight”, “fair” or “loose”. This is important in determining the amount of compression of the circumference. 1. Tight is recorded as “tight” if the tissue remains tightly in place during the test. 2. Normal If there is slight movement of the tissue in the residual limb, it is recorded as “normal”. This is similar to what happens to a normal person’s thigh when the muscle tissue is not contracted. 3. Flabby – If the residual limb tissues still move significantly during muscle contraction, it is recorded as “flabby”. This is a relatively subjective measurement. You need to be experienced and confident in classifying the residual limb in this way. Second, the structure of the sciatic accommodating cavity 1, the horizontal plane top view is important to create a mouth shape that first conforms to the physiological angle of the sciatic branch. Its accuracy will affect the success or failure of the production of the receiving cavity. According to the physiological anatomy, the angle is about 30 degrees for men and 45 degrees for women, which is only an approximate value and may be different in the actual assembly. 2.Receiving cavity size measurement 1.Compression measuring tape: measure one size at every 3cm from the sciatic tuberosity down. At 3 cm and 6 cm we apply the maximum compression. At 9 and 12 centimeters, we apply half the compression. The subsequent measurements are made by subtracting one centimeter from the actual measurement. The end of the measurement does not give the amount of compression. The so-called maximum compression and half of the compression, in fact, is the compression measurement ruler above the two springs, in measuring the maximum compression means that we hang two springs straight, if it is half of the compression means that we hang one of the two springs straight. 2. Determine the medial anterior-posterior distance dimension (A-P) Have the patient sit on an unpadded bench or flat chair and measure the distance from the bench to the anterior aspect of the longus tendon. To obtain accurate measurements, make sure the patient is sitting as straight as possible and locate the distance to the most proximal part of the anterior aspect of the longus tendon with the fingers. The measurement will be taken as close to the proximal end of the limb as possible. The normal anterior-posterior distance size varies widely. In most men, this size is between 70mm and 100mm. There are individual cases of greater than 110mm. Usually when this range is exceeded, the measurement may be incorrect. 3.Lateral anterior-posterior diameter measurement: let the patient stand to hold one side of the caliper against the other side of the caliper stuck to the rectus femoris muscle to ensure that the caliper is horizontal and the long axis is parallel to the line of travel let the patient contract the muscle and record the reading, pay attention to ensure that the pelvis is horizontal! 4. Determine the bony internal and external diameter dimensions (M-L): The bony internal and external diameter dimensions reflect the distance between the medial aspect of the sciatic bone in the coronal plane and the femoral stem at the inferior border of the greater trochanter. The first step in measuring the bony internal and external diameter dimensions is to locate the inferior sciatic branch and the sciatic tuberosity. From this point, the medial aspect of the sciatic bone is palpated. Place the short arm of the caliper on the medial aspect of the sciatic bone with the middle of the caliper directly above the sciatic tuberosity. If you place the short caliper arm too far forward along the body of the sciatic bone, the measurement will become larger. After placing the short arm of the caliper correctly on the medial side of the sciatic bone, place the long arm of the caliper comfortably in the plane below the greater trochanter and tighten the caliper until it is locked firmly in the anatomical position of the bone, making sure that the caliper is horizontal during the measurement. Keep the medial and lateral arms parallel to the line of travel. If you move the calipers from side to side, you should feel the pelvis moving together as if it were “locked” on the calipers. Take several measurements to ensure that the results are correct, and the results of consecutive measurements will not vary too much because the distance from bone to bone is recorded, therefore, the measurement value should usually be within a few millimeters of error. 5, bones inside – outside diameter: the distance between the upper edge of the medial sciatic bone and the distal end of the greater trochanter of the femur, measured with calipers at the appropriate angle of inversion, the distance is smaller in women than in men. The short arm of the caliper is clamped directly to the upper medial edge of the sciatic bone to ensure that the caliper is horizontal and the long arm is clamped to the lower edge of the lateral greater trochanter to align with the line of march. Make sure the pelvis is level and the femur is in the medial position. Pay attention to ensure that the pelvis level! 6.Measurement: soft tissue internal – external diameter: distance between the lower edge of the medial sciatic bone and the distal end of the greater trochanter, measured with calipers at the appropriate angle of internal retraction. 7.Measurement of diagonal position: 8.Measurement of the distance from the upper edge of the sciatic branch to the anterolateral side. 9.Measurement of pubic arch angle: Measure with one end of the measuring tape on the posterior side against the course of the bony branch and the other end parallel to the body’s direction of travel to record the reading. 10.Determine the iliofemoral angle: If the range of motion of the residual limb is not restricted, the iliofemoral angle of the residual limb can be reflected by measuring the iliofemoral angle of the healthy limb. Measuring the iliofemoral angle of the healthy limb will be more accurate because the healthy limb foot is fixed to the ground in the weight-bearing state. If the range of motion of the residual limb is limited, you will need to measure the iliofemoral angle on the residual limb. To measure the iliofemoral angle, the axis of the goniometer is placed at the apex of the greater trochanter. One side of the measuring arm is placed against the body along the femoral stem and the other side is placed against the body along the iliac bone. Have the patient try to shift the weight to the opposite side to bring the hip into prominence. If you are measuring a stump, make sure that the stump is as far inward as possible during the measurement. Do not press the goniometer into the soft tissues as this will cause the angle to be off. Typical iliofemoral angles are: 28-35° for men; 35-42° for women, slightly larger than for men. 10.Measurement: Iliofemoral angle measurement: If the abduction range of the residual limb is normal, you can also measure the healthy limb side and have the patient stand on the healthy limb side and project the hip to one side. 11.Measure residual limb adduction angle and residual limb flexion angle to check the range of motion of the hip joint on the residual limb side. 12.Measure residual limb length and mark (1)Use length gauge or anterior-posterior diameter gauge to determine the length of residual limb and femur. First determine the position of the pubic branch, hold the length gauge against the perineum and ensure that the long arm of the length gauge is perpendicular to the ground (as shown), slide the chassis to the end of the soft tissue, and record the length. Similarly, this is done by compressing the soft tissue, measuring the femoral length and recording it. (2) The length of the residual limb can also be determined using the sciatic tuberosity as a reference, but this is not a very reliable method and is easily influenced by the flexion/extension angle of the hip joint. (3) The length gauge is placed closely over the pubic symphysis branch and the circumference is marked every 30 mm or 50 mm (depending on the length of the residual limb) on the medial side of the residual limb. 13) Measurement of stump girth: (1) Problems often arise when measuring perineal girth. Due to incorrect method especially when the gluteal folds are measured in, the circumference size will be measured too large. (2) The correct method is to first ensure that the soft tape is placed directly below the pubic symphysis and that the stump is in the proper initial flexion and adduction angle. Make sure the circumference length is measured horizontally or with reference to the long axis of the residual limb, especially when the flexion contracture is obvious. It is important to practice the technique and discuss with your partner the steps to take: 1. Before applying the cast, you need to be completely sure that you can accurately find the location of the sciatic bone and the sciatic branch. Once several layers of plaster bandages are wrapped around the pelvis, it will be infinitely more difficult to accurately determine the location of these structures, especially when the plaster is almost dry. 2. If you are using a two-person model, discuss with your colleagues their respective responsibilities and how to work together to obtain a good model.