Total hip replacement precautions
Preventing hip dislocation
Total hip replacement precautions refer to the positions or movements that must be avoided following a total hip replacement in order to prevent the hip from dislocating. After total hip replacement surgery, the artificial ball and socket joint does not have the same mechanical stability as the original hip joint. Additionally, some of the ligaments and muscles that provide stability to the hip joint are affected, particularly for the first weeks following the surgery until natural healing of some of the soft tissue structures (muscles and ligaments) occur. For this reason, total hip replacement precautions must be followed in order to avoid hip dislocation, or joint separation, following total hip replacement surgery. Details of the types of movements that must be avoided, tips for preventing hip dislocation, and a video demonstration are included below. This information is general in nature and each surgeon may have their own specific total hip replacement precautions they want their patients to follow depending on the precise surgical technique they have used, and how stable the hip replacement was when tested during the surgery. In the first six weeks, total hip replacement precautions generally include avoiding hip flexion beyond 45 degrees (or 90 degrees depending on the surgeon), hip adduction beyond the mid-line of the body and hip external rotation beyond a neutral position. The meaning of these limitations are explained below.
Unstable total hip replacement positions
Total hip replacements can be unstable in certain positions. Movements that put the hip into less stable positions include hip flexion, hip adduction and hip internal rotation. These movements are explained below. The exact limitations that are prescribed as total hip replacement precautions during the first weeks following surgery may differ between each surgical technique, or even between two surgeons who use the same surgical approach. It is important to follow the precise limitations listed by the surgeon, as they will have a great deal of first hand experience working with their patients who have received the specific total hip replacement surgical technique used by that surgeon. Some surgeons may not prescribe any total hip replacement precautions, particularly if they have used what is known as an 'anterior' total hip replacement technique (where the surgical incision is made at the front of the hip).
Avoiding excessive hip flexion
Hip flexion occurs when the knee is moved closer to the chest (or the chest is moved closer to the knee). This may commonly occur by lifting the knee up, by bending over to pick something up off the ground, or by sitting down on a chair or bed. During the first 6 weeks many surgeons will advise you to avoid flexing the hip more than 45 degrees, others may suggest a 90 degree limitation. To put this in perspective, when you sit in a chair with your thighs parallel to the ground, you will be in a position of approximately 90 degrees hip flexion. In order to maintain less than 45 degrees of hip flexion when you sit down, you will probably need to sit in a chair that is higher than usual and keep the affected leg out quite straight when you sit down. This is particularly important to consider if you need to sit in a chair for a shower, particularly during the early stages of your recovery. Some chairs that can be used in a shower are often not high enough for people recovering from hip replacement surgeries. Regardless of the type of chair, If the chair is high enough and the leg can be kept out straight and away from the chair, the thigh bone can usually avoid being flexed up beyond 45 degrees as you sit. This is almost never the case when your foot is close to the base of the chair and flat on the floor. After a period of time (that your surgeon will advise you) the limitation of 45 degrees hip flexion is relaxed to 90 degrees hip flexion once the muscles and ligaments that provide stability have had a chance to heal and recover somewhat.
Avoiding hip adduction
Hip adduction occurs when the leg moves across the mid-line of the body (toward the other leg). A common example of this occurs when people cross their legs when their knees are straight. Avoiding hip adduction is generally easier than avoiding hip flexion. However, it is surprising how often we naturally cross out legs or feet when we are sitting or laying down (including sleeping). Hip adduction beyond the mid-line of the body should be avoided, particularly in the early stages following a total hip replacement. Avoiding hip adduction is another hip precaution intended to minimize the chance of hip dislocation.
Avoiding hip internal rotation
Hip internal rotation occurs when the leg is rolled inward. Avoiding hip internal rotation is another hip precaution intended to minimize the chance of hip dislocation following total hip replacement surgery. Similar to hip adduction, avoiding hip internal rotation is generally easier than avoiding hip flexion. However, it can be a little bit tricky to recognize when internal rotation of the hip is occurring. The easiest example of hip internal rotation is to consider having your legs out straight and rolling your leg inward so that your toes start to point inward toward the other leg. This type of movement should be avoided as part of the hip precautions following hip replacement surgery. In this example, it may seem as though the foot and toes are the only things moving, but the whole leg is actually moving (rotating) by pivoting at the ball and socket hip joint. Think of the whole leg turning like a dial, or the shaft of a door handle. Similarly, the same movement at the hip joint occurs when someone is standing on one leg and turns their body and pelvis toward that leg. In this scenario the nature of the movement at the hip is the same, except the leg (ball part of the hip) is remaining stationary and the body (socket of the hip) is rotating. This type of movement can easily occur when we are walking and change direction on the spot. For this reason, patients who have a total hip replacement are encouraged to keep stepping when they turn while walking (as opposed to turning by pivoting or twisting on the spot).
Higher risk of dislocation with combination movements
Each of the three types of movements included in the total hip replacement precautions, flexion, adduction or internal rotation, can put the ball and socket components of the total hip replacement in a less stable position. However, combining these movements can be even worse. In other words, the most unstable position for a total hip replacement is often combined hip flexion, adduction and internal rotation. Unfortunately some positions that we naturally use in day to day living may involve two or more of these movements and must be avoided. For example, someone sleeping on their left side may bend (flex) their right hip beyond 45 degrees and then let their right knee rest down on the bed in a position of hip adduction or internal rotation. In fact, one of the most challenging things in the first weeks after hip replacement surgery for some people can be finding a comfortable position to sleep in that does not place the hip at risk of dislocation. Pillows can be useful acting as a physical barrier, or mechanical prompt, to prevent hip movement into unstable positions while sleeping.
Tips for total hip replacement precautions
- Remember to only sit in a high chair, preferably with arms, and keep the affected leg out straight, away from the base of the chair. Avoiding sitting in low couches or soft chairs that you may sink down into and have difficulty getting out of.
- Make sure you use a high over toilet seat with a handrail frame that allows you to sit down to do your business while also allowing you to keep the affected leg out straight. This may sound like an odd tip, but sitting on a low toilet is probably the most common way people dislocate their hip. Over toilet seats are easy to hire or purchase from local pharmacies / drug stores as well as other medical aid specialty stores.
- Avoid bending over to pick things up off the ground; this will usually result in the body moving toward the knee (which puts the hip in a flexed position relative to the body).
- When turning around while standing or walking, take small steps while you turn. Do not pivot on the spot without moving your feet.
- When sleeping put a pillow between the knees to help prevent the leg from rolling in (hip internal rotation) or letting the leg cross the mid-line (hip adduction).