Hip hemiarthroplasty is a common orthopedic procedure, often performed to treat hip fractures in older patients. During this surgery, the damaged ball portion of the hip joint is replaced with an artificial implant, but the natural socket is left intact. Patients are instructed to follow “hip precautions,” which are specific movement restrictions designed to protect the new joint. These restrictions can be challenging for patients looking to regain independence. The necessity and duration of these precautions depend heavily on the surgical technique used.
The Primary Risk: Understanding Hip Dislocation
The primary reason for hip precautions is to prevent the serious complication of joint dislocation. During a hemiarthroplasty, the surgeon removes the natural ball and inserts the prosthetic component into the thigh bone. This procedure temporarily disrupts the soft tissues surrounding the joint, including the joint capsule and various muscles.
The stability of the new implant relies on the precise fit within the hip socket and the eventual healing of these surrounding soft tissues. Until the joint capsule and muscles have strengthened, the hip is temporarily more vulnerable to coming out of the socket. Certain extreme movements can leverage the new ball out of its position, requiring immediate medical intervention to relocate the joint.
Standard Precautions and Movement Restrictions
Traditional hip precautions are a set of three specific movement patterns patients are asked to avoid to keep the new joint seated securely.
Avoiding Excessive Flexion
This means not bending the hip past 90 degrees. Patients must avoid leaning forward to pick up items from the floor or sitting in low chairs where the knee is higher than the hip joint. Utilizing a raised toilet seat or a long-handled reaching tool helps patients maintain this angle limit.
Avoiding Adduction
This restriction involves avoiding crossing the operated leg over the midline of the body. This includes not crossing the legs while sitting and keeping a pillow between the knees when lying on the unoperated side.
Avoiding Internal Rotation
This is any movement that causes the toes of the operated leg to turn inward. Patients are advised to keep their toes pointed straight ahead or slightly outward when standing, walking, or lying down.
Are Precautions Necessary? Determining Risk by Surgical Approach
The most significant factor determining the necessity of hip precautions is the specific surgical approach used by the surgeon. Different approaches require varying degrees of disruption to the muscles and joint capsule, directly impacting the risk of dislocation.
The posterior approach, also known as the posterolateral approach, is traditionally associated with a higher risk of dislocation. This technique requires the surgeon to cut through or detach the short external rotator muscles and the posterior capsule to access the hip joint. Because these structures are important natural stabilizers, their temporary disruption makes the joint more vulnerable to dislocation. For patients who undergo this approach, full hip precautions are generally considered mandatory for a specific healing period to allow for soft tissue repair.
In contrast, the anterior and anterolateral approaches are often described as being more “muscle-sparing.” The direct anterior approach utilizes an interval between muscles, while the anterolateral or direct lateral approaches move or split muscles instead of cutting major stabilizing tendons at the back of the hip. This reduced soft tissue damage results in a significantly lower dislocation rate. Surgeons using these less-invasive techniques often prescribe modified precautions, minimal restrictions, or sometimes no precautions at all, depending on the patient’s stability and overall health.
When and How Precautions are Lifted
Precautions are a temporary measure, and the timeline for lifting them is determined by the healing of the soft tissues. Patients typically follow precautions for a period ranging from six to twelve weeks post-surgery. The six-week mark is a common minimum, as this time is required for initial soft tissue healing and scar formation to provide stability.
The final decision to lift or modify restrictions is made by the surgeon after a follow-up appointment and clinical assessment. Physical therapy plays an important role in this transition by helping the patient regain strength and confidence in the new joint. Precautions are gradually phased out as muscle strength returns and the therapist confirms the patient can safely perform a wider range of movements.