Risks & safety — the honest bit
Let's talk about the risks — honestly.
Every operation carries some risk, and we'd never gloss over that. The good news: serious complications are uncommon, and for most people the benefits far outweigh them. Here's the full, plain-English picture. But remember effort with physiotherapy is mandatory to gain the maximum improvement. Patient commitment in rehabilitation is paramount to achieve maximum success!
The big picture is reassuring.
Decades of data, on millions of patients, show that joint replacement reliably reduces pain and restores function — with serious complications affecting only a small minority. Most issues, when they do happen, are treatable.
Patients satisfied with their hip or knee replacement at one year.
Risk of a life-threatening complication in healthy adults.
Issues, when they happen, are treatable with timely care.
Figures are approximate and based on published joint-replacement registry and outcomes data; individual results vary.
How to read this page
The likelihood key.
Every risk below has a small coloured pill showing roughly how often it happens. We use the same scale throughout.
- Normal
Expected and not a complication.
- Common
Happens to some patients; usually minor or self-limiting.
- Uncommon
Happens to a small minority; treatable when it does.
- Rare
Very few patients; we plan carefully to prevent it.
Whole-body risks
Risks that affect the whole body.
These are risks that come with any major surgery, not just joint replacement.
Blood clots
Clots in the leg (DVT) or, rarely, the lung (PE). We routinely use blood-thinners, early walking, and compression to keep this low.
Heart attack & stroke
Major cardiac events around surgery are rare in healthy patients. Pre-operative screening helps identify and reduce risk.
Anaesthetic risks
Modern anaesthesia is very safe. Reactions and serious events are rare; anaesthesia-related death is very rare.
Bleeding / transfusion
Some blood loss is expected. Modern techniques and tranexamic acid mean transfusion is now uncommon.
Around the joint
Risks specific to the joint and the implant.
These relate to the joint itself, the implant, and the tissues immediately around it.
Infection
Deep infection around the implant is uncommon but serious. Strict sterile technique and antibiotics are used to prevent it.
Implant loosening or wear
Modern implants last 20+ years for most people, but over very long time-frames some can loosen or wear out.
Hardware irritation
Some patients can feel the implant under the skin or have mild irritation, especially in slim individuals.
Periprosthetic fracture
A fracture of the bone around the implant — uncommon, more so in older bone. May require additional treatment if it occurs.
Dislocation
Mostly relevant to hip replacement — the ball can come out of socket, especially in the first few weeks. Position and technique reduce this.
Leg-length difference
Small differences in leg length are common and usually well tolerated. Larger differences are rare.
Nerve or vessel injury
Major nerves and vessels run near the joint. Injury to them is rare and most minor nerve issues recover.
Stiffness
Some loss of range of motion can occur — especially in the knee — and is usually addressed with physiotherapy.
Ongoing aches
A small percentage of patients have some ongoing aches even after a technically excellent replacement.
A closer look
Infection.
Deep infection around an implant is one of the most serious complications of joint replacement — uncommon, but worth understanding in detail.
Periprosthetic joint infection
Around 1 in 100 primary hip or knee replacements in published registries — lower in healthy patients, higher with diabetes, obesity, or immune compromise.
- Antibiotics given before the incision.
- Sterile operating-room protocols.
- Pre-operative skin preparation and screening.
- Optimising blood sugar, weight, and skin health.
- Early infections — washout (open surgery to washout and change liner) and antibiotics.
- Established infections may need a staged implant exchange.
- Most infections, treated promptly, settle with good long-term function.
Totally normal after a knee replacement
NormalEvery knee replacement clicks or clunks a little — that's the sound of the new surfaces meeting, not a problem. And every knee replacement leaves a small numb patch on the front or outer side of the knee, because skin nerves are inevitably crossed by the incision. Both are expected and are not complications. Bruising, Swelling, Pain requiring narcotics for first few weeks are normal.
Knee-specific
Risks specific to knee replacement.
Peroneal nerve / foot drop
A nerve at the side of the knee can be stretched, mostly in severe deformity cases. Foot drop is rare and often recovers.
Extensor-mechanism injury
Injury to the quad tendon, patella, or patellar tendon. Rare, and minimised by quad-sparing techniques where appropriate.
Popliteal artery injury
The main artery behind the knee. Injury is very rare and avoided by careful technique and anatomical knowledge.
Hip-specific
Risks specific to hip replacement.
Dislocation
More relevant to hip than knee. Modern implants and approaches — including anterior — reduce this risk substantially.
Leg-length difference
A small difference is common; larger ones are uncommon. Templating and intra-operative checks help keep this minimal.
Anterolateral thigh numbness
A small skin nerve can be stretched with the anterior approach, leaving a patch of numbness on the outer thigh.
Femoral / sciatic nerve injury
Major nerves close to the hip. Injury is rare and most minor nerve issues recover over months.
What we do
How we keep your risk low.
Careful patient selection
Surgery is offered when it's likely to help and safe to perform. If you're not yet a good candidate, we'll say so.
Pre-operative optimisation
Blood sugar, weight, smoking, dental health, and other modifiable factors are addressed before the day of surgery.
Modern surgical technique
Muscle-sparing approaches, robotic-assisted knee and digitally navigated hip precision where appropriate, and meticulous sterile technique.
Multimodal pain & clot prevention
Modern anaesthesia, regional blocks, early walking, blood-thinners, and compression all work together.
Continuity of care
The same surgeon plans, performs, and follows your operation — so anything unusual is caught early.
Clear what-to-watch-for
You'll go home knowing exactly which symptoms need a phone call, and how to reach us if they happen.
The balance
For most people, benefits clearly outweigh risks.
When arthritis is significant and non-surgical options have been tried, the relief from pain and return of mobility usually weigh much more than the risks of the operation.
This balance is for illustration. We work the specifics out with you, for your case, at consultation.
This page is medically reviewed by Dr. Sharma, MD, FRCSC.
References
Where these figures come from.
- Canadian Joint Replacement Registry (CJRR) — Canadian Institute for Health Information.
- American Academy of Orthopaedic Surgeons (AAOS) patient information on hip and knee replacement.
- National Joint Registry (NJR) for England, Wales, Northern Ireland, the Isle of Man and the States of Guernsey.
- Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR).
- Peer-reviewed literature on periprosthetic joint infection rates and outcomes (e.g., Kurtz et al.; Parvizi et al.).
Disclaimer. The information on this page is general education about hip and knee replacement. It is not personal medical advice and is not a substitute for an in-person consultation. Risks, benefits, and alternatives for your specific situation can only be discussed in a clinical setting.