Which operation usually suits which patient

The practical split is this: when hip arthroplasty is being used after a displaced intracapsular hip fracture, total hip replacement is usually more likely in the fitter, more independent patient. NICE guidance from 2011 says to consider total hip replacement rather than hemiarthroplasty when the person could walk outdoors independently with no more than one stick before the fracture, is not cognitively impaired, and is medically fit for the procedure. Pre-existing osteoarthritis in the hip joint can also tilt the decision towards a total replacement in some patients.

Hemiarthroplasty more often suits older, less active or frailer patients. The AO Foundation describes it as a less complicated operation because it replaces only the femoral head and neck, rather than both sides of the hip joint, and says it generally gives satisfactory results for less active elderly patients. AO also notes a lower dislocation risk than total hip arthroplasty, although some patients may later develop acetabular pain or erosion.

Age on its own does not settle the choice. In the 2019 HEALTH trial, total hip replacement gave only a clinically unimportant improvement in function and quality of life over hemiarthroplasty at 24 months, with similar mortality and further-surgery rates, so patient suitability remains the main issue. In consultant-led assessment, the operation is matched first to mobility, cognition, medical fitness and joint condition; whether a muscle-sparing posterior approach such as SPAIRE hip replacement is appropriate is a separate step.

What each operation changes in the hip joint

Rather than revisiting who tends to have each operation, the useful picture here is the hip joint itself. In hip arthroplasty, damaged joint surfaces are replaced with prosthetic parts. The AO Foundation describes hemiarthroplasty as replacing the “femoral head and neck” only — the ball side of the ball-and-socket joint. Total hip replacement goes further, replacing that ball side and the socket lining as well, described by AO as the “acetabular surface”.

That difference matters when the socket is already worn. If osteoarthritis has affected both sides of the hip joint, a hemiarthroplasty leaves the socket surface behind, whereas a total hip replacement treats both the ball and the socket. AO Foundation notes that total hip arthroplasty is indicated when pre-existing osteoarthritis is present. This is also a separate question from surgical approach: SPAIRE hip replacement, for example, is a muscle-sparing posterior approach used to reach the joint, not a different implant type from hemiarthroplasty or total replacement.

Does total hip replacement give better results

Published evidence does not show a simple winner. A 2019 meta-analysis of displaced femoral neck fracture found that total hip arthroplasty appeared superior overall to hemiarthroplasty, and suggested recommending a total replacement for patients with a life expectancy of more than 4 years. That points to a possible functional advantage in selected patients who are likely to live long enough to benefit from it.

The strongest reality-check also came in 2019: the HEALTH trial, reported in NEJM and summarised by NIHR. In previously ambulatory adults aged over 50 with hip fracture, total hip arthroplasty produced only a “clinically unimportant improvement” in function and quality of life over 24 months. Further surgery was similar at about 8% in both groups, and mortality was similar too, at around 13%. In plain English, the average benefit of a full replacement was smaller than the headline debate can make it sound.

Even that 24-month comparison needs care. Outside a randomised trial, the two operations are not always being used in like-for-like patients, which makes older comparisons harder to interpret cleanly. That helps explain why NIHR’s summary favoured case-by-case decisions rather than a winner-takes-all view. The practical bottom line is that total hip replacement may give better results for some fitter patients, but the better operation overall is the one that matches the person’s baseline mobility, health and longer-term aims.

What recovery can patients realistically expect

In practice, the recovery arc after hemiarthroplasty or hip replacement is shaped heavily by the starting point. For displaced intracapsular fracture, the patients considered for total hip replacement are often those who were already walking outdoors independently, cognitively intact and medically fit; AO Foundation likewise describes total hip arthroplasty as more often used in more active elderly patients. That means a smoother recovery in the total-replacement group may partly reflect who was selected, not the implant alone. Modern hip arthroplasty pathways also focus on early mobilisation and recovery planning.

The practical expectation is less about a race between implants and more about staged gains in the early months: getting safely mobile, building confidence with transfers and daily tasks, and protecting stability while soft tissues heal. AAOS says dislocation risk is greatest in the first few months after total hip replacement, and a 2022 cohort found 52% of first dislocations occurred within 3 months. Recovery planning therefore needs to match baseline mobility, strength, cognition and medical fitness, rather than an idealised average.

When dislocation risk is highest and what changes it

Dislocation matters in this comparison because AO Foundation describes hemiarthroplasty as a less complicated operation with a lower dislocation risk than total hip arthroplasty. Even so, dislocation after primary total hip replacement is uncommon overall: a meta-analysis of 125 studies, covering about 4.63 million primary replacements, found a pooled rate of 2.10%. The practical message is mainly about timing. AAOS says the risk is greatest in the first few months while tissues heal, and a 2022 cohort of 155,185 primary total hip arthroplasties found that 52% of first dislocations happened within the first 3 months.

For the hemi-versus-total choice, the useful picture is not a long catalogue of predictors but the main groups of factors seen across studies:

• patient background: the large meta-analysis linked higher risk with greater comorbidity, neurological disorder and psychiatric disease;
• prior history and diagnosis: previous surgery such as spinal fusion, and some underlying diagnoses including avascular necrosis, rheumatoid arthritis and other inflammatory arthritis, were also associated with higher rates;
• implant and construct factors: the 2022 cohort linked dislocation within 2 years with cemented fixation and metal-on-poly or metal-on-metal bearings.

Some datasets also associate dislocation with younger age under 65, female sex and BMI under 20, but those links are not identical in every study. That is why stability discussions stay balanced rather than blaming one variable alone. Surgical approach may matter, but only as one part of the overall plan.

Which warning signs need urgent review

A sudden change matters more than ordinary postoperative aching. In a 2022 cohort study, 52% of first-time dislocations happened within the first 3 months after primary total hip arthroplasty, so new severe symptoms in the early weeks and months need prompt attention rather than watchful waiting at home.

• sudden severe hip or groin pain
• inability to move the leg normally
• inability to bear weight
• an obvious change in leg position, such as the limb looking twisted, shortened or out of place
• numbness, tingling or weakness in the foot or ankle

AAOS and Cleveland Clinic describe hip dislocation as a medical emergency. Those features can indicate a dislocation or another urgent postoperative problem after either hemiarthroplasty or total hip replacement. By contrast, expected recovery soreness is usually more gradual: bruising, stiffness and discomfort with movement, rather than a sudden dramatic loss of function. Symptoms of this kind still need same-day orthopaedic review or emergency assessment.

1. [1] *Incidence, timing, and predictors of hip dislocation following primary total hip arthroplasty for osteoarthritis*. (2022). https://doi.org/10.5435/JAAOS-D-22-00150 https://doi.org/10.5435/JAAOS-D-22-00150