Summary of Common Intraoperative Problems in Top Hip Arthroplasty (THA)

source:By Jason ChengNumber of Readings: secondRelease time:2019-08-10 09:44
1. What are the requirements for X-ray photography before joint surgery?

Anteroposterior radiographs of both hip joints, anteroposterior radiographs of the affected side, lateral radiographs of the affected side, and femoral abductor internal rotation radiographs of the hip joint are required.

Anteroposterior radiographs of both hips: the normal and affected sides can be compared, and the pelvis can be judged to be tilted or forward.

Anteroposterior film of the affected side: it is required to take a labeled radiograph, that is, to paste a 10cm metal marker ruler on the distal end of the greater trochanter on the outer side of the thigh, so as to eliminate X-ray amplification error and measure the size of acetabulum and medullary cavity more correctly. Lateral radiographs of the affected side: the acetabular cover of the hip joint can be observed.

Radiography of femoral abduction and internal rotation of the hip: the condition of the femoral neck of the affected limb can be observed.

2. Which surgical approach is the best choice for the joint?

Anterolateral approach: the incision begins in the middle of the iliac ridge, advances along the iliac ridge to the anterior superior iliac spine, and then extends 10-12cm to the outer edge of the patella. The lower end of the incision bends slightly laterally and posteriorly about 3-5cm. The anterolateral approach may result in the following complications: injury to the lateral femoral cutaneous nerve, circumflex lateral femoral artery, and increased outpouring of blood during the separation of tensor fascia lata and sartorius; Strayed into the medial space of sartorius or vastus medialis muscle may lead to injury of bone nerve and femoral artery. When separating the anterior medial side of the pseudo joint, the iliopsoas muscle was mistakenly detached from the small trochanter.

Posterolateral approach: the incision was made about 6cm from the outer and lower part of the posterior superior iliac spine, along the gluteus maximus fibers to the posterior margin of the greater trochanter of the femur, followed by the direction of the femoral shaft, extending downward about 5cm. It is the least disruptive approach to the hip structure. The posterolateral approach does not cause innervation of the gluteus maximus muscle because the gluteus maximus nerve enters from the lower gluteus maximus muscle fibers on the medial side away from the incision. However, there are complications such as sciatic nerve injury and inferior gluteal arteriovenous bleeding.

Lateral approach: the incision starts at 8cm below the greater trochanter and ends at 10cm above and up the lateral edge of the femur through the tip of the greater trochanter. Disadvantages of lateral incisions: the gluteus medius muscle is partially severed during surgery, and early postoperative gait may be affected.

3. Placement position of acetabular hook?

The usual position of the Hohmann retractor is: the first one is inserted in front of the acetabulum, retracting the sartorius muscle and the vastus medialis muscle; The second is inserted just above the back of the acetabulum and retracts the gluteus muscle; Place the third under and in front of the acetabulum.

4. How to dislocate the hip joint during operation?

Dislocate the joints by buckling, adduction and internal rotation of the lower extremities to avoid violence. If dislocation is difficult, the cause should be found. If necessary, the femoral neck can be cut off and the femoral head removed.

5. How to determine the osteotomy line in femoral neck osteotomy?

The osteotomy location should be determined according to the preoperative design. Generally speaking, the femoral spur 1-1.5cm vertical femoral neck osteotomy should be retained above the small trochanter, and the comparison of osteotomy guide plate or medullary cavity file should be referred to.

6. Acetabular exposure is difficult. This is a common problem. What are the main reasons?

Problems with the incision, the cause of the position, inadequate exposure, patient obesity, and bleeding can all contribute to the difficulty of exposure. One of the more common reasons is that the posterior capsule is removed thoroughly from the posterior approach, but the anterior capsule is not removed at the end of the acetabular margin. This can lead to poor exposure, especially if the capsule has contractures.

Iliopsoas problems, when patients have a pre-existing hip or old fracture, are often accompanied by contracture of the iliopsoas muscle, which requires the iliopsoas muscle to be cut so that the acetabulum can be clearly exposed.

Then there is the quadratus femoris problem. In the posterior approach, the external rotator cuff needs to be cut off, such as the piriformis, the superior gemellus, etc., but when the quadratus femoris is more developed and the muscles are more powerful, if the muscles are not cut off, they will not be able to rotate internally, and they will also affect the exposure of the acetabulum.

7. How to clean the acetabulum before file the acetabulum?

Extend the lower limbs and rotate inside, use the acetabular retainer to fully expose the acetabular area, clear the osteophytes around the acetabulum, the joint capsule and the soft tissue inside the acetabulum, and pay attention to protect the transverse acetabular ligament.

8. Does the glenoid lip need to be removed when the acetabulum is exposed? Is it necessary to remove osteophytes on the glenoid lip?

Because the osteophytes on the labrum can cause collisions during joint movement, they must be removed.

The labrum needs to be cut off before the outer cup, otherwise it will not show well and affect the Angle of implant of the outer cup. In addition, if the labrum is not resected, the soft tissue on the labrum may be brought into the acetabulum during the external cup, which may affect the fixation effect. After the cup is filled, the excess bone is carefully removed with a bone knife or bone-cutter. If osteophytes are cut before the outer cup, they may destroy the shape of the bone acetabulum and affect the fixation of the outer cup.

9. Is it necessary to remove the transverse ligament of the acetabulum?

It should not be removed. For two reasons, first, the acetabulum transverse ligament can keep acetabulum foreign cup tensity, can make it to implant acetabular cup to achieve a better pressure distribution function, if the transverse ligament is cut off, to affect the elasticity of the acetabulum, diamond joint outer cup is cement, cultured is pressure distribution and the initial stability, if the initial stability is bad, prosthesis is easy to loose, causing the failure of the bone ingrowth. Secondly, there is the obturator artery acetabular branch below the transverse ligament. Once the transverse ligament is cut off, it is easy to damage the blood vessel. After the injury, the blood vessel quickly retract, resulting in hemostasis difficulty during the operation. Moreover, if too much tissue is removed below the transverse acetabular ligament and below the acetabular incision, it is easy to injure the femoral nerve. So during surgery, try not to remove the transverse ligament. It can be said that the transverse ligaments of the acetabulum must be preserved when using a non-cement cup.

10. When using acetabular files, what size do you usually start with?

It is recommended to start with a small acetabular file and gradually increase it, or start with a file two sizes smaller than the femoral head.

Note that the bottom of the acetabulum, especially around the round ligament socket, is prone to osteogenesis. When using a large acetabular file, it is difficult to file the hyperplasia of the round ligament socket at the bottom of the acetabulum or the cartilage around the round ligament socket, so start with a small file.

When using a small file, pay attention to the force and direction of use. Special attention should be paid to the grinding and filing of the cartilage around the round ligament fossa. Only the surrounding cartilage needs to be rubbed away, and sometimes bone grafting is needed in the fossa. If also flattened in the round ligament socket, it may cause most of the bone in the rest of the acetabulum to be filed too deeply.

The osseous acetabulum is not a true semicircle and is different from the shape of the acetabular file. The purpose of an acetabular file is to remove the cartilage and expose the subchondral bone; The shape of the bone acetabulum is consistent with the shape of the acetabulum file. After the acetabular file is worn out, it is necessary to make the acetabulum form a true semicircle, which is consistent with the shape of the acetabular file and the outer cup. If the shape is not consistent, pressure match is not good.

11. Can the acetabular cup screw reach the contralateral cortex?

Do not reach the contralateral cortex. The cup screw should be inserted into the cancellous bone. Acetabular locking screws are cancellous bone screws that can easily damage blood vessels in the pelvic wall if they hit the opposite cortex.

12. When screwing in acetabular cup screws, why are some screw tighter and others looser?

It is common to find cystic changes in the subchondral bone after filing the acetabulum. Be sure to remove the contents of the capsule wall with a scraping spoon, and then implant the bone. If it is not seen on the X-ray before surgery and is not detected in time during surgery, the above problem may be encountered, that is, the mortar cup screw hits into the bone of cystic changes, the screw must feel loose. If the second nail feels particularly loose and the first nail has been hit, remove the loose nail and insert small bone grains into the hole. And good, strong nails do not have to re-drive, as long as it is not loose. When driving the nail, if the first nail is skewed or the force is not applied, when re-screwing the nail, the bone must be inserted inside the nail hole to re-screwing the nail, so as to avoid loosening of the screw.

13. What are the problems to be noted when inserting acetabular screw?

When you drill a hole, don't drill too deep. If you drill too deep, because the drill bit is much thinner than the screw hole, it will cause the direction of the nail hole is not easy to grasp. The rule of thumb is to punch through the subchondral bone to a certain depth. In acetabular screw, cancellous bone self-tapping screw can be screwed in only by paying attention to the direction. If the initial stability after the outer cup is good, the acetabular screw may not be used. Theoretically speaking, the acetabular screw should have an impact on the stability of the cup, which is due to the change of force direction and increase of initial stability. But in this case, the acetabular screw breaks a few years after it is placed, and the cup remains intact.

14. Must the inside and outside cup be used? Is it to punch the outer cup on the inner cup directly, then operate the femoral part, or to install the inner cup and the outer cup test model first, after testing with the medullary cavity file and the test model head, before entering the prosthesis, then install the inner cup and the outer cup?

It is necessary to use the inner and outer cup test mold, because after the inner and outer cup product is driven, when the tightness of hip joint is tested with the medullary cavity file and the neck and neck test mold head, the inner cup friction damage will be caused. In addition, the inner cup is designed to prevent dislocation on the high side, that is, the inner cup and the outer cup are rotated to find out the possible dislocation Angle to determine the position of the high side.

15. When the acetabulum is not well exposed, how to place the inner cup?

If the acetabulum is well exposed and the doctor is skilled, the cup can be implanted by hand, with two thumbs on both sides, press, and then hit the cup with the acetabular lining impactor, note that the lowest point of the impactor corresponds to the highest point of the lining, do not use violence.

16. How to fully expose the femoral osteotomy surface?

For example, in the posterior lateral approach, both the hip and knee joint flexed 90°, the hip joint was adducted, and the assistant supported the knee joint to exert backward force. At the same time, two plate hooks were placed on the neck of the femur, and the other plate hook was tilted from the end of the osteotomy to the anterior edge of the femoral neck, which could fully expose the osteotomy surface of the femur.

17. How to protect the sciatic nerve? Prevent stretching of the sciatic nerve?

If the posterolateral approach is used, usually when the external rotator muscle group is exposed, the fat mass is visible behind. The fat mass is sciatic nerve. It can be exposed first, protected and then cut off the external rotator muscle group. If skilled, it is not necessary to expose the sciatic nerve, and the nerve and the fat mass can be pulled apart together.

18. What problems should be paid attention to when cutting the external rotation muscles?

Extension and internal rotation of lower limbs should be made to tense the external rotator muscles and expose the termination point of the external rotator muscles behind the greater trochanter. The external rotator muscle should be cut off near the insertion point, and the fat tissue outside the joint capsule should be bluntly separated to expose the joint capsule.

19. Do intramedullary files have to be used from the smallest size?

The principle of using the medullary cavity file is that it should be in place in one step, but it should be according to the specific situation.

It is best to file the medullary cavity once in place if the surgeon is proficient in the operation of the non-cement prosthesis and has a good command of the power and rhythm of the filing. However, it is not always emphasized that it must be in place at one time. If the patient's bone is very good, and the shape of the medullary cavity is not very clear, the doctor is unfamiliar with the operation of non-cement prosthesis, which is easy to cause problems. It is difficult to insert the medullary cavity file, which is related to the direction, shape and size of the medullary cavity file, insufficient bone clarity under the great trochanter, and cortical hyperplasia of the medial femoral calcar.

20. How to deal with proximal femoral splitting fracture during operation?

Proximal femoral fracture is often prone to occur in the solid fixation of the femoral prosthesis without cement. During intraoperative operation, the surrounding soft tissues should be cleaned to see the periphery of the femoral calcar. If the fracture occurs, expose the distal end of the fracture line and determine the extent of the fracture. If the fracture is not clearly separated, steel wire binding can be used.

21. How to judge the tightness of the hip joint and the good position of the prosthesis after the installation of the hip prosthesis test model during the operation?

Normally, no dislocation during hip flexion 120 °, 30 ° abduction and adduction 20 ° no obstruction, head of mortar coverage rate of 50% is appropriate, the check the joints of lower limbs and longitudinal pull tension are for reference only, because of the surrounding soft tissue dissection degree of joint looseness has a great influence, which has been widely in the surrounding soft tissue dissection, too much emphasis on joint looseness is bound to cause lower limbs extend, can consult preoperative postoperative great trochanter tip and the distance of the acetabulum confirm the length of the lower limbs.

22. If the joint is tense during the operation and cannot be repositioned, can the iliopsoas muscle be cut off?

Firstly, the source of joint tension should be determined. If it is due to the contracture of the anterior joint capsule, firstly release this part; secondly, the short neck collar should be selected as the model test. If the above methods have been used and the joint cannot be reduced, the iliopsoas muscle can be cut off, but the bending force will be weakened after the operation.

23. How to deal with dislocation after operation?

Postoperative dislocation is related to many aspects: surgical approach, improper placement of prosthesis, impact of femur and acetabular margin, placement of lower limbs after surgery, etc. If the femoral and acetabular implants are in the wrong or unstable position, the implant should be removed immediately and re-implanted. If the position of the prosthesis is acceptable, manipulative reduction can be performed under anesthesia. After reduction, the lower limbs should be placed in mild external rotation, while the anterior instability of the hip joint should be placed in internal rotation, or bone traction for 4-6 weeks to stabilize the joint. In the case of subluxation with no pain or slight discomfort, the affected limb should be placed outside the booth for 3 weeks or longer. Reoperation should be considered for obvious poor placement of prosthesis or insufficient abductor muscle tension, repeated dislocation after reduction, or failure of reduction.

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