When you need a new knee
Posted on 21 August 2014
Knee-replacement surgery can change your quality of life significantly – and, as with everything else, advancements in medicine have made the operation safer and more successful than ever. Dr Peter Smith takes us through the procedure.
Picture the scene: it’s the mid-1950s and a patient is being prepped for knee-replacement surgery. Arthritis has crippled him, eating away at his knee joint to such an extent that it has deformed the joint and left him in constant agony.
The operation is still in its experimental stages and doctors do it as a last resort. He is anaesthetised and surgeons go to work, cutting open his leg from thigh to calf to expose his femur and tibia bones. In an operation lasting three to four hours his knee joint is replaced with a simple hinged joint. The risk of post-op infection is high, recovery is slow and the new knee won’t give very good results.
After the surgery, he’s taken to the critical care unit where he’ll spend at least a week. Up to three months in a general unit follow, and it will be a full year before the pain and discomfort starts to abate. He still has to walk with crutches and will probably always have to get around with some form of aid. If he’s lucky, his new knee will last five years.
Things are very different today. ‘Knee-replacement surgery is now a highly successful procedure when it comes to patient satisfaction,’ says Dr Peter Smith, an orthopaedic surgeon at Mediclinic Milnerton in Cape Town. ‘Patients are left with a scar of just 20cm, as opposed to one that ran almost the entire length of the leg.’
A total knee-replacement (TKR) operation typically lasts about 90 minutes. It’s a highly sophisticated process, with computer technology helping surgeons determine exactly where to cut and how to align the new knee and balance soft tissue.
Most of the changes, Dr Smith explains, have made the procedure safer. ‘Some of the most feared complications are infection and deep-vein thrombosis (DVT), but the use of prophylactic antibiotics (antibiotics given to prevent an infection as opposed to treating an existing infection) have reduced this danger significantly.’
Blood clots and fatal embolism have been reduced with anticoagulant medicine and surgical stockings. ‘We mobilise the patients a lot quicker today, which decreases the risk of DVT,’ he says. ‘Over the past five years patient-specific bone-cutting guides and patient-specific surgical instruments have been developed. These are made with the help of CT and MRI scans of the patient’s knee taken before the operation.’
Three-dimensional printing is sometimes used to make a prosthetic, especially where the surgeon has to deal with bone loss. However, 3-D printing is not widely used in TKR surgery in South Africa, says Dr Smith.
The quality of the prostheses used has drastically improved and the new joint – made with titanium among other materials – mimics the knee joint, which means patients can walk far easier. Physiotherapy after the op is vital, though, adds Dr Smith.
And how long do today’s new knees last?
‘They can work for up to 20 years,’ says Dr Smith. ‘But patients need to be realistic – over time it may be necessary to replace a part or all of the components.’
Who needs it?
A bad injury that didn’t heal properly, a chronic illness, and wear and tear are all reasons for knee-replacement surgery. However,?the majority of total knee replacements are performed on the elderly. Years of use causes cartilage to crack and wear away, which results in bones rubbing together and becoming rough and pitted. A prosthesis alleviates pain and increases mobility.
You’ll need some help getting around right after your op. Crutches and walkers are usually recommended, and it’s best to rent them as you probably won’t need them for long. Pharmacies and medical supply stores have a wide range for sale and rent.
New lease on life
Sheila Whitfield’s left knee started troubling her about 10 years ago. ‘I’d turned 70 so I guessed it was just something that went with age,’ she says. ‘I had some injections for the pain and an arthroscopy (minimally invasive surgery to diagnose and treat knee pain) and just got on with it.’
Then, five years ago, disaster struck. A Baker’s cyst – normally a benign swelling in the knee – burst in her other knee. This caused severe cellulitis, which led to septic arthritis. Sheila was admitted to Mediclinic Pietermaritzburg for a total knee replacement (TKR) in March 2010 but she was in bad shape – she went into renal failure and had to be stabilised before they could operate.
She spent several days in high care after the operation before being transferred to a general unit. Eight days later, she was discharged into the respite care facility at her retirement village. Recovery was slow but once she was better, she began to consider having her other knee fixed. The pain from arthritis, her doctor told her, would only get worse.
In January 2012 she returned to Mediclinic Pietermaritzburg for her second TKR – and, after all the drama of the first, this one ‘was a doddle’.
‘It was painful, yes, but I had a spinal block at first and then painkillers so it was manageable. I had a fantastic surgeon, a brilliant family doctor and the nurses, especially the ones in high care, were great,’ she says.
‘My physiotherapist came to see me the day after each op and started on gentle movements, lifting and bending the leg,’ Shelia explains. ‘She also encouraged me to start walking again almost immediately. I was very diligent about physio and I think it made all the difference.’
Sheila tried crutches after both ops. ‘I didn’t like them,’ she says. ‘I used a walker for a while, then just a stick, then nothing unless I was going for long walks.’ These days Sheila (now 80), a mom of three, grandmother of eight and great-grandmother of one, leads a full, active life. She walks at least 2km every day, plays croquet and cheers on her grandsons from the side of sports fields. ‘Having new knees has improved my quality of life immeasurably,’ she says. ‘I’d recommend it to anyone.’
British surgeon Dr Leslie Gordon Percival Shiers, the pioneer of knee-replacement surgery, publishes his original papers on the procedure in the Journal of Bone and Joint Surgery.
Dr Shiers refuses to patent his invention, choosing instead to demonstrate the operation around the world and invite other surgeons to improve on his idea. Early operations aren’t a huge success – they consist of hinged implants that don’t work well and come with a high rate of infection.
More advanced implants, called condylar total-knee implants, are designed. They come in only two sizes and are solid pieces. Orthopaedic surgeons ?are wary of them at first because of the bad history of hinged implants. But, as more success stories are told, they become more confident and more operations are performed.
Implant companies design prostheses that are easier to place and better instruments that make the surgery easier to perform.
Partial and total knee-replacement surgery is widely accepted, with excellent results when it comes to easing pain from arthritis. The manufacture of the mechanism continues to improve. Today a combination of metal and plastic is used to ensure maximum mobility.
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