Key messages:
- Patient-specific cutting guides (a technique in which a patient undergoes a scan of the knee which is used to make a customised cutting block to perform a total knee replacement) do not help in producing more accurately aligned components compared to conventional cutting guides.
- No meaningful differences between patient-specific guides against conventional or computer navigation have been found regarding implant survival, re-operation rate, complications, function or pain.
- Computer-assisted navigation (using software during knee replacement) may improve the precision of overall lower-limb alignment and tibiofemoral sagittal alignment (alignment looking side on at the knee) compared to patient-specific guides.
What is Total Knee Replacement (TKR)?
TKR is a treatment for terminal, painful arthritis of the knee joint.
During TKR, the worn bony ends of the knee joint are cut away and replaced with metal and plastic components designed to smoothly move and function like a normal, healthy knee joint.
During surgery, how surgeons perform the bone cuts and then position or align the new components is vital to the success of a TKR.
What is a patient-specific cutting guide or computer-assisted navigation in TKR?
Traditionally in TKR, metal rods placed within or outside the femur and tibia are used to place conventional cutting guides (CON) to facilitate bone cuts and implant placement.
Computer-assisted knee replacement uses intraoperative mapping of the patient's knee joint and computer-assisted navigation (NAV) for bone cuts.
In patient-specific cutting guides (PSG), a preoperative investigation (CT or MRI scan) is used to create a 3D knee model. Cutting guides are then made specifically for each patient. PSG are postulated to help better align implants, reduce operative time and blood loss, and produce better function after TKR.
What did we want to find out?
We wanted to find out if PSG improves survival of implant, pain, function and precision for overall lower limb alignment compared to conventional guides and computer-assisted navigation in TKR.
What did we do?
We searched for studies comparing PSG with conventional surgical cutting guides or computer-assisted navigation used in TKR surgery. We compared and summarised the results of these studies, rating our confidence in the evidence based on factors such as study methodology and size.
What did we find?
We included 44 randomised controlled trials with 3664 people (64.3% female) aged between 63 and 74 years.
38 out of 42 randomised control trials compared PSG to conventional TKR cutting guides, 2 compared PSG to computer-assisted navigation and 2 trials compared PSG to both conventional cutting guides and computer-assisted navigation. Outcomes were largely reported around two years after the surgery.
Main results
Conventional instrumentation (CON)
Compared to CON, PSG had little benefit:
Survival of implant:
1 out of 100 people underwent revision of the implant following PSG.
2 out of 100 people underwent revision of the implant following CON.
Function (12-60, 12 is best function):
People who had PSG rated their function as 13.44 points.
People who had CON rated their function as 15.1 points.
Precision in lower limb alignment as measured by the proportion of outliers for femorotibial coronal angle: (a radiographic outlier is an x-ray measure of thigh and shinbone alignment after TKR looking at how components and bones are lined up if looking from the front of a patient):
19 out of 100 people reported radiographic outlier events with PSG.
22 out of 100 people reported radiographic outlier events with CON.
Pain (lower scores mean less pain):
People who had PSG rated their pain as 15.8 points.
People who had CON rated their pain as 17.4 points.
Total adverse events (infection, blood clots):
10 out of 100 people reported adverse events with PSG.
10 out of 100 people reported adverse events with CON.
Re-operations:
4 out of 100 people reported re-operations with PSG.
5 out of 100 people reported re-operations with CON.
Computer-assisted navigation (NAV)
Compared to NAV, PSG had little benefit:
Function (higher scores mean better function):
People who had PSG rated their function as 57.5 points.
People who had NAV rated their function as 52.5 points.
Precision in lower limb alignment (proportion of outliers for femorotibial coronal angle):
19 out of 100 people reported radiographic outlier events with PSG.
9 out of 100 people reported radiographic outlier events with NAV.
What are the limitations of the evidence?
PSGs do not appear to offer a clear advantage in producing more accurately aligned components in TKR, or in improving precision of lower limb alignment except for improving the rotation of the femoral component. PSG may result in no difference in pain, function, adverse events, or re-operation compared to conventional cutting guides.
NAV may improve the precision of lower limb alignment compared to PSG. We are uncertain of clinically meaningful differences between PSG, CON and NAV when analysing implant survival, re-operations performed and complications.
How up to date is this evidence?
The evidence is up-to-date as of 21st January 2025.
Pročitajte cijeli sažetak
Accurate alignment of components is considered important for improved outcomes when restoring lower limb alignment in total knee arthroplasty (TKA). Patient-specific guides were developed with the intention of improving surgical efficiency, accuracy of component positioning and overall limb alignment. Currently, the benefits of patient-specific guides in achieving these goals and whether this has an impact on clinical and functional outcomes remains unclear.
Ciljevi
To assess the benefits and harms of patient-specific cutting guides versus conventional cutting guides or computer-assisted surgical navigation in people undergoing primary TKA.
Metode pretraživanja
We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid), Embase (Ovid) and trial registers up to 21st January 2025, unrestricted by language.
Kriteriji odabira
We included randomised controlled trials (RCTs) comparing patient-specific cutting guides (PSGs) to conventional instrumentation (CON) or computer-assisted surgical navigation (NAV) in TKA. Major outcomes were survival of implant (risk of revision), function, radiographic lower limb alignment, pain, global assessment, total adverse events and re-operation rate.
Prikupljanje podataka i obrada
We used standard methods recommended by Cochrane.
Glavni rezultati
Forty-four studies with 3664 participants were identified. Out of these, 40 studies with 3134 participants compared PSG to CON, two studies with 140 participants compared PSG to NAV and two studies with 390 participants compared PSG to NAV and CON. Regarding the imaging modality, 27 trials used magnetic resonance imaging (MRI)-based PSGs, 18 trials used computed tomographic (CT- based PSGs and 2 trials used both CT-based and MR-based PSGs). The mean age of participants ranged from 63 years to 74 years. Fifty-three per cent of participants were male, with more than 90% of participants having knee osteoarthritis. Most of the included trials were at risk of bias; 25/44 (56.8%) studies were at risk of selection bias, and 39/44 (88.6%) were at risk of performance and detection biases.
1. PSGs compared to conventional instrumentation
Compared to conventional instrumentation, PSGs may result in little to no difference in survival of the implant. At 26 months, 7/347 participants (20 per 1000) in the conventional instrumentation group reported survival of implant (risk of revision) compared to 4/342 participants (16 per 1000) in the PSG group (RR 0.79 (95% CI 0.25 to 2.52); I² = 0%; 689 participants; 9 studies; low-certainty evidence downgraded for bias and imprecision).
Compared to conventional instrumentation, PSGs may result in little to no improvement in function. Mean function (KSS, OKS, WOMAC, KOOS) was 15.1 points with conventional instrumentation and 13.44 points with PSG (SMD -0.11, 95% CI -0.25 to 0.03 back-translated to MD 1.66 points lower (95% CI 3.77 points lower, 0.45 points higher; I² = 56%; 23 studies, 1913 participants; low-certainty evidence downgraded for bias and indirectness)) at short-term (up to two years).
PSGs may result in little to no difference in precision in lower limb alignment as measured by the proportion of outliers for femorotibial coronal angle (FTCA). At up to two years, 266/1208 participants (220 per 1000) in the conventional instrumentation group reported radiographic outlier events compared to 234/1204 participants (189 per 1000) in the PSG group (RR 0.86, 95% CI 0.68 to 1.10, I² = 49%; 29 studies, 2412 participants; low-certainty evidence downgraded for bias and imprecision).
Low-certainty evidence, downgraded for bias and indirectness, showed that PSGs may result in little to no difference in pain. Mean pain (0 to 100 scale, 0 no pain) was 17.4 points with conventional instrumentation and 15.8 points with PSG (SMD -0.09, 95% CI -0.23 to 0.06, back-translated to MD 1.52 points lower (95% CI 3.88 lower, 1.01 higher; I² = 0%, 10 studies, 715 participants)).
None of the included studies provided data on global assessment.
Low-certainty evidence, downgraded for bias and imprecision, showed that PSGs may result in little to no difference in adverse events. Total adverse events (infection, thrombosis) were reported in 60/590 participants (102 per 1000) in the conventional instrumentation group compared to 61/579 participants (99 per 1000) in the PSG group (RR 0.97, 95% CI 0.68 to 1.39, I² = 5%, 14 studies, 1169 participants).
Low-certainty evidence, downgraded for bias and imprecision, showed that PSGs may result in little to no difference in re-operation rates. Re-operations were reported in 21/424 participants (50 per 1000) in the conventional instrumentation group compared to 16/419 participants (44 per 1000) in the PSG group (RR 0.87, 95% CI 0.45 to 1.68, I² = 0%, 10 studies, 843 participants).
2. PSGs compared to computer-assisted navigation
Low-certainty evidence (downgraded for bias and imprecision) showed that, compared to computer-assisted navigation, PSGs may result in little to no difference in function. Mean function (0 to 100, 100 best function) was 52.5 points with computer-assisted navigation compared to 57.5 points with PSGs at the short term (less than two years): MD 5.00 points higher (95% CI 1.31 lower to 11.31 higher, I² = 0%, 2 studies, 120 participants).
Low-certainty evidence (downgraded for bias and imprecision) showed that use of PSGs may result in worse precision in lower limb alignment compared to computer-assisted navigation. At the short term (less than two years), 13/135 participants (96 per 1000) in the computer-assisted navigation group reported radiographic outlier events compared to 28/135 participants (196 per 1000) in the PSG group (RR 2.04, 95% CI 0.87 to 4.82, I² = 44%, 3 studies, 270 participants).
None of the included studies provided data on survival of the implant, global assessment, pain, re-operations or adverse events.
Zaključak autora
Low-certainty evidence showed no meaningful differences with regard to survival of implant, re-operation rate, adverse events, function, pain, and global assessment when comparing patient-specific cutting guides to conventional instrumentation or to computer-assisted navigation in total knee arthroplasty.
