PRM interventions in total hip and knee arthroplasty. Preoperative preparation, early and subsequent postoperative rehabilitation. Functional assessment and prevention of complications

01What the operation changes

A total hip arthroplasty replaces the femoral head with a metal or ceramic ball on a stem in the femur, and lines the acetabulum with a cup. A total knee arthroplasty caps the end of the femur and the top of the tibia with metal and puts a plastic insert between them, often with a button on the back of the patella. Parts are fixed with bone cement or pressed into bone that grows onto them. The usual reason is end-stage osteoarthritis when conservative care has failed (see rehabilitation in osteoarthritis); others are rheumatoid arthritis, femoral neck fracture and avascular necrosis.

The new joint does not hurt, but the patient arrives with years of limping: weak, wasted muscles, a short stride, stiff tissues and a habit of protecting the leg. Surgery adds a wound, swelling and a cut capsule. Rehabilitation has to rebuild everything the pain took away, while protecting the new joint until the soft tissues heal (about six weeks).

02Functional assessment

Assessment is done before surgery, as a baseline, and repeated through each phase (general method in functional assessment).

03Preoperative preparation

The better the state a patient goes into surgery, the faster they come out of it. Preparation is called prehabilitation.

• Education (often a group "joint school"): what will happen, how pain is controlled, that walking starts at once, the precautions, the length of stay. Patients who know what to expect are less anxious and leave hospital sooner.
• Exercise: quadriceps and hip strengthening, range of motion, aerobic fitness, breathing exercises.
• Practice with crutches or a frame, and the transfers they will use after surgery (bed, chair, toilet, car).
• Home ready: a raised toilet seat, a chair with arms of the right height, rails, a clear path without rugs, things within reach; a long-handled reacher and sock aid for hip patients.
• Medical optimisation with the team: weight, smoking, diabetes, anaemia, skin and teeth (sources of infection).

04Early postoperative rehabilitation

First days (0 to 2 weeks): protect, control pain and swelling, get moving

Modern care follows enhanced recovery: good pain relief, no unnecessary drains or catheters, and a first walk on the day of surgery or within 24 hours.

1. 1

   In bed, from the first hours

   Deep breathing and coughing; ankle pumps every hour awake, for the calf pump; isometric quadriceps and gluteal squeezes; heel slides.
2. 2

   Out of bed, day 0 or 1

   Sit on the edge of the bed, stand and walk a few metres with a frame, with weight as tolerated unless the surgeon says otherwise.
3. 3

   Before going home

   Walking with crutches, getting in and out of bed, chair and toilet, and stairs: up with the good leg first, down with the operated leg first, the crutch going with the operated leg.
4. 4

   At home

   A daily exercise programme, ice for swelling, and walking a little more each day.

Weight-bearing: with cemented and most modern uncemented implants, patients may put as much weight on the leg as they can tolerate from the first day. The surgeon restricts it only after bone grafting, a fracture during surgery, or some revision operations.

Hip: avoid dislocation

The joint is most at risk in the first six weeks, while the cut capsule and muscles heal. Which position is risky depends on the approach the surgeon used.

In practice: a firm chair with arms and a raised toilet seat, a pillow between the knees in bed, no bending down to pick things up or put on socks (a reacher and sock aid instead), turning by stepping round rather than twisting on the operated leg.

Knee: straighten first

• Full extension: a rolled towel under the heel, not under the knee, and quadriceps contractions pushing the back of the knee down. No pillow under the knee, which is comfortable but trains a flexion contracture.
• Flexion: heel slides, sitting with the foot sliding back under the chair, a static bike once the knee bends enough for a full turn (about 110 degrees, a little less with the seat raised; rocking back and forth comes first).
• The quadriceps switches off after knee surgery (arthrogenic muscle inhibition): swelling and pain reflexly stop it contracting. Early quadriceps work, ice and NMES of the quadriceps help bring it back.
• Continuous passive motion machines bend the knee automatically. They add little to a good active programme and are not used routinely.

05Subsequent rehabilitation

After the first two weeks the aim moves from protection to rebuilding: strength, endurance, balance and a normal walk.

Daily tasks are practised as exercises: walking with and then without aids, stairs, sitting down and standing up, getting in and out of a car (sit first, then swing both legs in together), dressing, washing and housework.

at most, from surgery to the start of rehabilitation

24hoursat most, from surgery to the start of rehabilitation

for capsule and muscle to heal; most return to driving about now

6weeksfor capsule and muscle to heal; most return to driving about now

of knee flexion, the early target; stairs and chairs need about 90 to 110

90degreesof knee flexion, the early target; stairs and chairs need about 90 to 110

Sport: walking, cycling, swimming, golf, dancing and doubles tennis are encouraged. Running, jumping and contact sports load the implant heavily and wear it out faster, so most surgeons advise against them.

Physical modalities

Modalities ease pain and swelling so the patient can exercise; they never replace exercise.

06Prevention of complications

Each complication has a cause, and the prevention follows from it.

The team: the orthopaedic surgeon, the physiatrist, the physiotherapist (rehabilitator), the occupational therapist for the home and daily tasks, the nurse, the psychologist when fear of moving holds the patient back, the dietitian, and the patient and family.