Hip replacement surgery in adults

This review assessed evidence from randomised controlled trials (RCTs) and quasi-RCTs, on the benefits and harms of different types of hip replacement used to treat hip fracture in adults.


A hip fracture is a break at the top of the leg bone. These types of breaks are common in older adults whose bones may be fragile because of a condition called osteoporosis. One method of treatment is to replace the broken hip with an artifical one. This can be done using a hemiarthroplasty (HA), which replaces part of the hip joint (the ball part of the joint). These replacements can be unipolar (a single artificial joint), or bipolar (with an additional joint within the HA). Alternatively, surgery may replace the whole hip joint, which also includes the socket in which the ball of the hip joint sits - this a total hip arthroplasty (THA). Both of these artificial joints can be fixed in place with or without bone cement.

Search date

We searched for RCTs (clinical studies where people are randomly assigned to treatment groups), and quasi-RCTs (in which people are put into groups by a method which is not randomised, such as date of birth or hospital record number) up to 6 July 2020.

Study characteristics

We included 58 studies, involving 10,654 adults with 10,662 hip fractures. Study participants ranged from 63 to 87 years of age, and 71% were women, which is usual for people who have this type of hip fracture.

Key results

Cemented HAs compared to uncemented HAs (17 studies, 3644 participants)

We found that cemented HAs improve health-related quality of life (HRQoL) and reduce the risk of death at 12 months after surgery. The sizes of these benefits ranged from a small to a large effect. There may be little or no difference between treatments in the ability to use the hip (functional status), but this evidence was very uncertain. Whether or not the HA is cemented probably makes little or no difference to performance in activities of daily living (ADL) or the ability to walk independently, how many people experience confusion after surgery (delirium), die within four months of surgery, or need additional surgery. Most complication risks were similar, but we noted that some risks related directly to hip replacement surgery (such as causing a break during surgery) were increased with uncemented HAs.

Bipolar HAs compared to unipolar HAs (13 studies, 1499 participants)

The type of HA probably makes little or no difference to how many people die within four months or up to 12 months after surgery, and may make little or no difference to the need for additional surgery. No studies reported four-month ADL and functional status. The evidence was very uncertain whether using a bipolar or unipolar HA makes any difference to delirium or HRQoL within four months of surgery. Again, complication risks were similar, and we found no evidence of a difference in the risk of hip dislocation.

THAs compared to HAs (17 studies, 3232 participants)

We are uncertain whether ADL, functional status, delirium, mobility, or deaths within four months or up to 12 months after surgery are different between these treatments. The evidence did not show a difference in the risk of additional surgery but we could not exclude the possibility of an important benefit of THA. Although the risk of most complications was similar, hip dislocation is increased with THA.

Certainty of the evidence

The evidence for many of the comparisons is based on only a few participants, and many studies used methods which may not be reliable. Most of the evidence for ADL, functional status, HRQoL, and independent walking was of low and very low certainty, meaning that we are not confident in the findings. We had limited confidence or were moderately confident in our other findings.


For people having a HA, it is likely that a cemented replacement produces a better outcome overall than an uncemented replacement. There is no evidence to suggest that a bipolar HA leads to different outcomes from a unipolar HA. The differences between a total hip replacement and partial hip replacement are small and may not be clinically important.

Authors' conclusions: 

For people undergoing HA for intracapsular hip fracture, it is likely that a cemented prosthesis will yield an improved global outcome, particularly in terms of HRQoL and mortality. There is no evidence to suggest a bipolar HA is superior to a unipolar prosthesis. Any benefit of THA compared with hemiarthroplasty is likely to be small and not clinically appreciable. We encourage researchers to focus on alternative implants in current clinical practice, such as dual-mobility bearings, for which there is limited available evidence. 

Read the full abstract...

Hip fractures are a major healthcare problem, presenting a huge challenge and burden to individuals and healthcare systems. The number of hip fractures globally is rising rapidly. The majority of hip fractures are treated surgically. This review evaluates evidence for types of arthroplasty: hemiarthroplasties (HAs), which replace part of the hip joint; and total hip arthroplasties (THAs), which replace all of it.


To determine the effects of different designs, articulations, and fixation techniques of arthroplasties for treating hip fractures in adults.

Search strategy: 

We searched CENTRAL, MEDLINE, Embase, seven other databases and one trials register in July 2020.

Selection criteria: 

We included randomised controlled trials (RCTs) and quasi-RCTs comparing different arthroplasties for treating fragility intracapsular hip fractures in older adults. We included THAs and HAs inserted with or without cement, and comparisons between different articulations, sizes, and types of prostheses. We excluded studies of people with specific pathologies other than osteoporosis and with hip fractures resulting from high-energy trauma.

Data collection and analysis: 

We used standard methodological procedures expected by Cochrane. We collected data for seven outcomes: activities of daily living, functional status, health-related quality of life, mobility (all early: within four months of surgery), early mortality and at 12 months after surgery, delirium, and unplanned return to theatre at the end of follow-up.

Main results: 

We included 58 studies (50 RCTs, 8 quasi-RCTs) with 10,654 participants with 10,662 fractures. All studies reported intracapsular fractures, except one study of extracapsular fractures. The mean age of participants in the studies ranged from 63 years to 87 years, and 71% were women.

We report here the findings of three comparisons that represent the most substantial body of evidence in the review. Other comparisons were also reported, but with many fewer participants.

All studies had unclear risks of bias in at least one domain and were at high risk of detection bias. We downgraded the certainty of many outcomes for imprecision, and for risks of bias where sensitivity analysis indicated that bias sometimes influenced the size or direction of the effect estimate.

HA: cemented versus uncemented (17 studies, 3644 participants)

There was moderate-certainty evidence of a benefit with cemented HA consistent with clinically small to large differences in health-related quality of life (HRQoL) (standardised mean difference (SMD) 0.20, 95% CI 0.07 to 0.34; 3 studies, 1122 participants), and reduction in the risk of mortality at 12 months (RR 0.86, 95% CI 0.78 to 0.96; 15 studies, 3727 participants). We found moderate-certainty evidence of little or no difference in performance of activities of daily living (ADL) (SMD -0.03, 95% CI -0.21 to 0.16; 4 studies, 1275 participants), and independent mobility (RR 1.04, 95% CI 0.95 to 1.14; 3 studies, 980 participants). We found low-certainty evidence of little or no difference in delirium (RR 1.06, 95% CI 0.55 to 2.06; 2 studies, 800 participants), early mortality (RR 0.95, 95% CI 0.80 to 1.13; 12 studies, 3136 participants) or unplanned return to theatre (RR 0.70, 95% CI 0.45 to 1.10; 6 studies, 2336 participants). For functional status, there was very low-certainty evidence showing no clinically important differences.

The risks of most adverse events were similar. However, cemented HAs led to less periprosthetic fractures intraoperatively (RR 0.20, 95% CI 0.08 to 0.46; 7 studies, 1669 participants) and postoperatively (RR 0.29, 95% CI 0.14 to 0.57; 6 studies, 2819 participants), but had a higher risk of pulmonary embolus (RR 3.56, 95% CI 1.26 to 10.11, 6 studies, 2499 participants).

Bipolar HA versus unipolar HA (13 studies, 1499 participants)

We found low-certainty evidence of little or no difference between bipolar and unipolar HAs in early mortality (RR 0.94, 95% CI 0.54 to 1.64; 4 studies, 573 participants) and 12-month mortality (RR 1.17, 95% CI 0.89 to 1.53; 8 studies, 839 participants). We are unsure of the effect for delirium, HRQoL, and unplanned return to theatre, which all indicated little or no difference between articulation, because the certainty of the evidence was very low. No studies reported on early ADL, functional status and mobility.

The overall risk of adverse events was similar. The absolute risk of dislocation was low (approximately 1.6%) and there was no evidence of any difference between treatments.

THA versus HA (17 studies, 3232 participants)

The difference in the risk of mortality at 12 months was consistent with clinically relevant benefits and harms (RR 1.00, 95% CI 0.83 to 1.22; 11 studies, 2667 participants; moderate-certainty evidence). There was no evidence of a difference in unplanned return to theatre, but this effect estimate includes clinically relevant benefits of THA (RR 0.63, 95% CI 0.37 to 1.07, favours THA; 10 studies, 2594 participants; low-certainty evidence). We found low-certainty evidence of little or no difference between THA and HA in delirium (RR 1.41, 95% CI 0.60 to 3.33; 2 studies, 357 participants), and mobility (MD -0.40, 95% CI -0.96 to 0.16, favours THA; 1 study, 83 participants). We are unsure of the effect for early functional status, ADL, HRQoL, and mortality, which indicated little or no difference between interventions, because the certainty of the evidence was very low. 

The overall risks of adverse events were similar. There was an increased risk of dislocation with THA (RR 1.96, 95% CI 1.17 to 3.27; 12 studies, 2719 participants) and no evidence of a difference in deep infection.