Patient-Specific Instrumentation: What to Expect

Patient-specific instrumentation uses a three-dimensional plan and custom-made guides to help the surgeon prepare the bone during selected joint replacement procedures.

The guides are designed from imaging of your joint. They fit onto particular bone surfaces and indicate where surgical instruments should be positioned. This is different from a standard instrument set, which is selected from a range of sizes during the operation. The technology supports the surgeon's plan; it does not perform the operation or decide which implant is appropriate.

Before surgery, the clinical team obtains the imaging needed for planning and sends the relevant measurements to the instrument manufacturer or planning service. The surgeon reviews a proposed plan, including alignment and bone preparation, and may adjust it before guides are produced.

In the operating room, the surgeon exposes the joint and checks that each guide matches the intended bone surface. The guide helps position instruments for planned bone cuts or other preparation. The surgeon can reassess the plan during the procedure and use conventional instruments if the guide does not fit or the operative findings call for a different approach.

A guide reflects the imaging and the plan used to create it. Changes in positioning, unexpected bone damage, access to the joint, or the guide's fit may mean that the surgeon modifies the plan or uses another instrument. The technology cannot correct every alignment issue and does not remove the need for surgical judgement.

Patient-specific instrumentation is not suitable for every person or every procedure. Your surgeon may recommend it only when the imaging is adequate and the planned operation can benefit from a custom guide. Ask whether the technology changes the incision, the implant choice, the rehabilitation plan, or the expected hospital stay in your specific case.

A surgeon can prepare the joint with standard instruments selected during the operation. Some teams use computer-assisted navigation to show the position of instruments during surgery. Robotic-assisted systems may also support planning or instrument control, depending on the procedure and equipment available. These approaches differ in how planning information reaches the operating room; the surgeon remains responsible for the operative decisions.

For an overview of the operation in which this technology may be used, see the page on [Total Knee Replacement](/treatments/joint-replacement/total-knee-replacement/).

You may have an additional imaging appointment or a planning discussion before surgery. Bring details of previous operations, metalwork, injuries, or difficulty positioning the joint, because these can affect planning. The custom guides are prepared for the planned procedure and are not a reusable personal device.

The presence of a custom guide does not by itself predict how quickly you will recover. Recovery still depends on the operation, your general health, pain management, wound care, movement exercises, and the rehabilitation plan. Confirm which activities are allowed at each stage and when the team wants you to report increasing pain, swelling, wound drainage, fever, or calf symptoms.

The guide is checked for fit during the operation, and the surgical team can change technique when needed. As with the underlying operation, discuss the possible harms, alternatives, anaesthesia, infection precautions, blood-clot prevention, and rehabilitation before consenting.

Useful questions include: What imaging is needed? What happens if the guide does not fit? Will standard instruments be available? Does this change my rehabilitation instructions? Which symptoms after surgery need an urgent call?