Rebuilding the Unstable Knee

Dr Putra Vatakal, Orthopaedic Surgeon, Malaysia, Kuala Lumpur, Selangor, Subang Jaya Medical Centre Centre, acl reconstruction, acl tear

Moving into a new phase of Malaysia’s war on COVID, one regularly forwarded phone message lists the DOs and DONTs of what is increasingly known as MCO 2.0.

One item of interest to the more athletically inclined Malaysian is “What sports (or exercise) can I still do?” – which usually centres around jogging, badminton and contact sports (like football)- things that most of us take for granted, but which can greatly challenge those who have an unstable knee. 🤸🏻‍♂️⛹🏻‍♀️🤾🏻

And speaking of unstable knees…

Q: How does a knee become unstable?

The knee is like a complex machine.

The thigh and shin bones are like the solid chassis of a car…🚗

They provide support for everything else.

The ligaments that surround and connect the bones are the bodywork built over the chassis. The muscles enveloping it are the pistons of the engine, the smooth cartilage covering the bones are the wheels that spin to help us move.

Really, when any part of the knee fails, it can cause it to become painful and unstable…. but, most often, when the ligaments that hold the knee together get injured (specifically the Anterior and Posterior Cruciate Ligaments – ACL & PCL), the result is a knee that wobbles and clunks around when you walk fast or run.

Q: When is an unstable knee a problem?

Most of the time, building up the large muscles around the knee can help an unstable knee become stable enough for daily activities. But it can put the brakes on your ability to run, exercise and play sports. 🏃🏻‍♀️

Some of my patients find that they gain weight because their lifestyles become slower paced – which isn’t a good thing. 🙆🏻‍♀️

Q: So.. can a torn knee ligament be repaired?

Good question. Some knee ligaments (like the medial and lateral collateral ligaments – MCL & LCL) can be repaired when torn, and they can even sometimes heal on their own (usually with a knee brace).

But the two deep knee ligaments (again, the ACL and PCL, which most commonly cause instability) float around within the thick fluid inside your knee, and do not heal well, even when they are repaired.

So ACL and PCL (and some other ligaments) need to be recreated when they are torn. We need to fashion a new ligament, and let it grow and heal inside your knee before you can go back to actively running, jumping and playing sports.

Q: How do you recreate an ACL Ligament?

The most common way is to take a tendon from a different part of your knee and modify it to be used as a new ACL. This is safe because we take (or harvest) tendons that can be safely removed (usually a hamstring tendon from the back of the knee). This is called a hamstring autograft. ‘Auto’ simply means it comes from your own body.

The alternative is to use a tendon or ligament that has been harvested from an organ donor. Some people feel squeamish (I believe the technical term is ‘geli’) about having a part of a dead person inside them, but really it is quite safe. This is called an allograft – which means that the graft (the part used to create the new ACL or other ligament) comes from another person.

Because there is a lot of work involved in processing and storing (in deep freeze) allografts from organ donors, they can be quite expensive, and so I mostly use them when I need to recreate multiple ligaments for the same patient.

As medical (and biotech) research progresses, there are increasingly more synthetic ligaments available. Made of materials with names I can’t pronounce (like polyester, Gore-Tex, Dacron, et cetera), these synthetic grafts have been shown to be better than natural grafts in some cases.

It may take some years before they are widely used, but in my experience, they can be life-savers in desperate situations.

Take the case of Azizul, the 36 year old amateur hockey player who busted his right ACL while scoring a goal in the last few seconds of the match. He lay anaesthetised with his limbs strapped to the icy OR table as Dr Roshan Gunalan and I scrolled through his MRI.

Some years before, while Azizul was busy at work, a colleague had backed a forklift into his knee, slashing it open, requiring 16 stitches. 🚑

Now, as the nurses laid out the drapes and filled little steel pots with concentrated iodine, I ran my fingers along the pale scar on Azizul’s knee.

“I can feel the hamstring tendons there,” I called out to Dr Roshan.

Unfortunately, they weren’t.

10 minutes later, the front of Azizul’s knee lay open, but the hamstring tendons were nowhere to be seen… gone in that long forgotten forklift accident.

If we hadn’t been all scrubbed up, we would have scratched our heads in dismay.

So, out came the synthetic graft to save the day, in went the arthroscope… and today Azizul, the bionic man 🦾 is well on the way to recovery.

Overly dramatic? Perhaps. A real story? Yes.Synthetic grafts may well be the future of joint reconstruction.

Originally written on 13 December 2021 in Subang Jaya Medical Centre, Selangor

Image credits: Luis Yap

Note: Names and some details have been changed to protect patient privacy.