Knee pain when driving: the kneecap, the pedals, the back of the knee and driving after surgery

Kneecap pain and the long bendStrong evidence

NHS inform lists pain after keeping a sitting position for a while, such as driving or at the cinema, among the symptoms of patellofemoral pain syndrome, and sitting or driving for a long time among its contributing factors. In 458 people with kneecap pain, 249 (54.4%) had problems with prolonged sitting with the knees bent; they were younger, more often women and had more pain overall.

An international consensus lists pain on sitting, getting up after sitting or straightening the knee after sitting as a supporting feature rather than an essential one; the standard kneecap questionnaire asks about prolonged sitting with bent knees because it picks out kneecap problems; and a US physiotherapy guideline lists prolonged sitting among the activities that make it worse.

Sources 1, 2, 3, 4, 5

How common it is in people who drive for workEmerging evidence

Knee pain affected about 1 in 5 professional drivers across 16 studies (21.8%): 22.3% of lorry drivers, 14.1% of taxi drivers and 31.7% of bus drivers. In 1,242 taxi drivers in Taiwan, knee pain over a year was 11% in those who drove up to 6 hours a day and 22% in those who drove more than 10; that study looked at one point in time, so it can't show the driving caused it, and most long-hours drivers had no knee pain.

Sources 6, 7, 8, 9, 10

The pedals and the clutchMixed evidence

No study has shown that the clutch or the pedals cause knee pain. In lab studies, the clutch movement followed the seat and pedal positions, and working lorry pedals mainly used the hamstrings, the calf and the front thigh muscle, with seat height changing the load. Our reading: a seat too far back straightens the knee onto the pedal under load, and too close keeps it bent tightly, which a sore kneecap dislikes. An NHS trust's seating leaflet says knees should be slightly bent when the pedals are fully pressed.

Sources 11, 12, 13

Arthritis, and why pain can slow brakingEmerging evidence

From mid-life, stiffness and pain for the first steps after a drive, easing as you get going, are typical of knee arthritis. Arthritis can also slow braking: in a real car cabin with a clutch pedal, right knee arthritis slowed braking, and left knee arthritis slowed the reaction and the foot's movement as much as the right; in 137 people with arthritis, median braking took 696 milliseconds with the knee against 592 with the hip. How bad the X-ray looked didn't predict braking. The authors suggest joint pain may hold back the muscles' response.

Sources 14, 15, 16

The back of the knee, and the clot signEmerging evidence

A seat that is too long presses behind the knee; an NHS health board says make sure the seat is not too long, to avoid pressure behind your knee. Pain or fullness behind the knee when it's bent can be a Baker's cyst, a tendon or the back of the meniscus. A calf that becomes painful, swollen or red after a long journey can be a clot: the NHS lists long journeys of more than 4 hours among the times a clot is more likely. That is rare, but it needs a same-day check.

Sources 17, 18

Telling the causes apart, and when a scan mattersStrong evidence

Kneecap pain is recognised from the history and examination; the map above gives the first clues. The National Institute for Health and Care Excellence (NICE) says don't routinely use imaging to diagnose osteoarthritis unless the features are unusual, and X-ray severity didn't predict braking in knee arthritis. A scan matters after an injury with swelling, for a knee that locks or gives way, and, for a suspected clot, an urgent ultrasound scan.

Sources 3, 19, 16, 18

How it usually goesEmerging evidence

NHS inform suggests talking to a professional if kneecap pain hasn't improved within 6 weeks of changing your activities and doing the exercises; the US guideline notes it can last for years in some people. After a right knee replacement, people rated their own driving good again at about 6 weeks, when braking force and reaction time were back to their levels before surgery. No one can promise a date.

Sources 1, 5, 20

The seat and the pedals: guidance, not trialsEmerging evidence

No trial has tested a driving change for knee pain. An NHS trust's seating leaflet: knees slightly bent when the pedals are fully pressed, moving the seat forward or back to get it. Another trust: move the seat far enough forward to reach the pedals easily. An NHS health board: make sure your feet reach the pedals without stretching, and the seat isn't so long it presses behind your knee. NHS inform's advice for kneecap pain includes regular breaks from the activities that bring it on. An NHS pain clinic and Arthritis UK suggest an automatic if the clutch is a struggle.

Sources 13, 21, 17, 1, 22, 23

Strength is the main treatmentStrong evidence

Hip and knee strengthening is the core treatment for kneecap pain in the international consensus and the US guideline, as our runner's knee and knee pain when sitting guides set out with their trial numbers. For knee arthritis, NICE says offer therapeutic exercise tailored to the person, such as local muscle strengthening and general aerobic fitness, and warns that joint pain may rise when you start. No trial has tested exercise for knee pain when driving.

Sources 3, 5, 19

After a knee replacement: braking comes back within weeks for mostEmerging evidence

These studies measured braking in simulators, mostly set up like an automatic car. Across 9 studies, braking was back to its level before surgery by about 4 weeks after a right and 2 weeks after a left knee replacement; across 12 studies, total braking time didn't differ from before surgery, but moving the foot from the accelerator to the brake was slower at 2 and 4 weeks and back from 6. Braking force fell by about a third in the first week after a right replacement in one study (and by a quarter after a left), and in another, pedal force and reaction time were back by 6 weeks. People with knee arthritis brake more slowly than people without it, even before surgery, and some ended up braking faster than before.

Recovered braking isn't readiness: of people back to their braking level 2 weeks after a right knee replacement, only 67% felt ready to drive. After a left replacement, right-foot braking barely changed, but only in an automatic car, because the left knee works the clutch. After a partial replacement, right-side braking was back by 6 weeks in one study (which carries an erratum we couldn't read).

Sources 24, 25, 26, 20, 27, 28, 29, 30, 31, 32

After ACL surgery or an arthroscopyEmerging evidence

Across 5 studies of ACL reconstruction, braking was back to normal about 4 to 6 weeks after a right-sided and 2 to 3 weeks after a left-sided operation, in automatic-car set-ups; the one study in a simulator with a clutch needed 4 to 6 weeks whichever side was operated on. People actually drove again after an average of 13 days (right) and 10 days (left), well before braking had recovered. The kind of graft changed the timing in one small study.

After a right knee arthroscopy, braking slowed from 736 milliseconds before the operation to 920 at 1 week, and was 685 at 4 weeks; pooled across arthroscopy studies, it met its baseline after about 6 weeks.

Sources 33, 34, 35, 36, 37, 38, 39

In a cast, a boot or a braceEmerging evidence

In healthy volunteers braking with the right leg, an above-knee cast added almost 3 metres to stopping distance at 30 miles per hour, and a walking boot or short cast slowed braking too (from 0.580 seconds in a shoe to 0.619 in a walker boot in one study). A brace that limits knee bending slowed braking, but a kneecap brace, a ligament brace, an unloading brace for arthritis and an elastic bandage didn't. These are simulator studies in volunteers, not patients.

Sources 40, 41, 42, 43

What these studies mean, and long journeysStrong evidence

Braking studies give a best case for when people can return to driving, and people often drive before their braking has recovered. The studies' own suggestions average about 5 weeks after knee surgery but vary, surgeons are told to weigh other factors too, and one study's authors say categorical statements can't be made. They are small, mostly automatic set-ups, and some disagree: never permission to drive.

Long journeys raise the risk of a clot a little: about 18% more for each extra 2 hours of travel by any means, with car journeys similar to flights, in studies of all kinds of travel rather than car data. After surgery the risk is higher, so ask your team before a long journey.

Sources 44, 45, 24, 26, 46, 47, 18

The seat and the pedals (written steps)

Our 3D figure can't show these. They come from NHS trusts and a health board (two leaflets past their review dates), NHS inform, an insurer's magazine and an NHS pain clinic; our suggestions are labelled. None has been tested for knee pain.

• 1. Move the seat until your knees are slightly bent with each pedal pressed fully (an NHS trust's seating leaflet).
• 2. A seat length that leaves a gap behind the knee (an NHS health board).
• 3. Seat height so you can see the road and your thighs are supported (an NHS trust).
• 4. At every stop, straighten each knee a few times and walk (our suggestion; NHS inform advises regular breaks from what brings kneecap pain on).
• 5. Cruise control on the motorway, when it's safe, so you can move your legs (an insurer's magazine passing on chiropractors' tips; untested).
• 6. An automatic, if the clutch is a struggle (an NHS pain clinic). In a manual car, use neutral in queues rather than holding the clutch down (our suggestion; untested).

Sources 13, 17, 21, 1, 48, 22

Long journeys (written steps)

These come from the Highway Code, the NHS and an NHS trust; our suggestions are labelled.

• 1. A break of at least 15 minutes after every 2 hours of driving, as the Highway Code recommends for tiredness and an NHS trust's leaflet for stiffness; sooner while your knee is sore (our suggestion).
• 2. Journeys of 4 hours or more: wear loose clothing, drink plenty of water, avoid alcohol and walk around when you can, as the NHS advises to lower the risk of a clot.
• 3. After knee surgery, ask your team before a long journey: our ACL surgery guide's warning signs say so for the first weeks.

Sources 49, 18, 13

Driving after knee surgery, in a cast or a brace (written steps)

No one can give you a date. Your surgeon or doctor advises whether you're fit to drive, you are legally responsible for being in control, your insurer decides whether you're covered, and the DVLA only needs to know in the cases below. These are the rules in their own words.

• 1. After a knee replacement, the NHS says wait at least 6 weeks to drive after a total replacement or 3 weeks after a partial one, and check with your doctor that you're fit to drive.
• 2. After ACL surgery, the NHS says don't drive until your medical team says you're fit to, and tell your insurer.
• 3. After an arthroscopy, the NHS says you must not drive if you've had a general anaesthetic, and that you should be able to drive again when you've fully recovered and can do an emergency stop, usually at least 2 weeks after the operation.
• 4. GOV.UK's guidance for doctors says drivers don't need to tell the DVLA about recovery from surgery unless it is likely to affect driving and last more than 3 months; limb injuries expected to recover normally are among the temporary conditions the treating clinician judges; and you must stay in control and stay insured. GOV.UK says you must tell the DVLA about a limb disability.
• 5. If your doctor tells you to stop driving for 3 months or more, GOV.UK's pages differ: its medical conditions guide says you must surrender your licence to the DVLA, and its licence page says you can surrender it voluntarily and must still tell the DVLA about the condition if you don't.
• 6. Insurers: the Royal College of Surgeons' knee replacement page (an archived copy; the page has been removed) said your insurer should be told, as some companies won't insure drivers for a number of weeks after surgery. One insurer says you shouldn't drive after any medical procedure until your doctor says it's safe, and in a survey of 16 UK motor insurers about plaster casts, driving against the doctor's advice was likely to invalidate the policy.
• 7. The same college page said you should be free of the sedation of painkillers and able to control the car, including freely performing an emergency stop. Once your team agrees, practise pressing the pedals firmly in a parked car with the engine off first.

Sources 50, 51, 52, 53, 54, 55, 56, 57, 58, 59

Long drives come back (written steps)

No trial has tested how driving comes back after knee pain. These steps are our suggestion unless a source is named.

• 1. Add 15 to 30 minutes at a time while the knee stays within the pain rule.
• 2. Straighten each leg and walk at every stop; a stop at least every 2 hours (the Highway Code), sooner while you're building back.
• 3. Manual cars in heavy traffic come last.
• 4. Journeys of 4 hours or more: walk about at stops, loose clothing and water (the NHS).
• 5. If it hasn't improved within 6 weeks, or it's getting worse, see a GP or physiotherapist (NHS inform).

Sources 49, 18, 1