Parental allograft – father’s hamstring used for child’s PCL

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This case presentation is of an 11 year old boy who had a posterior cruciate ligament (PCL) reconstruction using parental donation - innovative not only because of the use of parental live allograft tissue but also because it was a PCL reconstruction in a very tiny patient. 

He had suffered a posterior knee dislocation during a judo session in September 2014. The dislocation was reduced in A&E (emergency department) and the limb was put into a splint, and he was sent through to me.

When I examined him he was a good few months down the line – so a chronic case – but extremely lax, I could really push his tibia a long way posteriorly so he was an extreme example of a PCL rupture and he interestingly didn’t seem to have a huge amount of laxity in the collateral ligaments or the post lateral corner so it seemed like an isolated PCL with posterior capsule disruption which is extremely unusual given the fact that on his original presenting x-rays he had completed dislocated the knee posteriorly.If I had got to him early I would have gone for an internal brace and repair but he came through chronically and then the decision becomes much more difficult as PCL surgery in children is not something that is even discussed at any of the meetings. During my training I have never seen anyone present a case of a small child having a PCL reconstruction.​

Paediatric PCL reconstruction is rarely performed, and is a very difficult operation in someone this small. Usually PCL injuries heal up well without surgery, and one would expect this to be even more so in a child. However, in this particular instance the lad had suffered a very nasty knee dislocation and he was left with a very unstable knee. He was referred to me by another orthopaedic specialist knee surgeon

The videos of his knee show instability very clearly at the EUA and you can see on the video how the tibia can be pushed forward relative to the femur because of the lack of posterior stabilising structures. Fortunately there wasn’t a major issue with the collateral ligaments and so it was just an isolated PCL that I had to treat. From the imaging he must have had a posterolateral corner injury but this had in fact healed up and he’d be left with just this isolated PCL deficiency.

knee dislocation in a 9 year old child

X-rays showing the dislocation - it is not difficult to see that the tibial and femur are totally out of alignment

knee dislocation in a child

When I first met our patient he was a very small 9 year old lad who was really struggling. I tried to go down the route of conservative management with bracing and physiotherapy. For the two years in the brace he wasn’t able to engage in any sport or fool around with his friends in the playground. He felt himself alienated from the other boys and stigmatised by the brace. He is by nature very shy young chap and after the knee injury he became really very withdrawn and found it very difficult to cope with school. He got to the point where his parents had to seek counselling to try and help him because he became so withdrawn and they were so concerned about his mental health. 

When he came to see me 3 or 4 months ago - now aged 11 - he was in such a sad, sorry state that I felt really that it was time to consider surgery and I started discussions in earnest with his mother and father. In Basingstoke we have a license for live parental allograft tissue, and I thought he would be a very good case for this so we decided to go for surgery and we decided to use his father’s hamstring tendon - his semitendinosus - which gave us a fantastic graft actually.

We certainly prefer the patient’s own tissue wherever possible, but in this young person his own tissue would have been inadequate. Using live allograft from a related donor means that it’s virtually the same as using your own tissue - it’s fresh and has not been in any way treated, and it has therefore excellent biomechanical properties.

The PCL is the most difficult ligament to reconstruct in an adult although this is now fairly straightforward for a specialist knee surgeon, but the instruments which are designed for adults also weren’t the appropriate size for a young boy so it made the operation very challenging.

In the operating theatre (OR) we first harvested both hamstring tendons from his father - which of course didn’t take a huge amount of time - and used our standard operating procedures to safely store these for a few minutes whilst we closed up the incisions - and then we brought our young patient in.

PCL procedure

At arthroscopy we found the child's joint surfaces were actually in good shape and both menisci were also intact. I very carefully dissected down the back of his tibia under direct vision and we were able to use a standard guide to put ourselves into a good position to drill the tunnel for the graft.

However, when it came to drilling the femur the normal guides that we use were too big, so I had to use a freehand technique to make the tunnel in the appropriate position underneath his growth plate.

I was very happy with the result and when the graft went in the knee felt beautifully stable and I was delighted with the outcome that we achieved.

PCL reconstruction in a child

Tibial tunnel drilled under fluoroscopic control

Femoral tunnel dL reconstruction in child

Femoral tunnel drilled freehand

Showing the final fixation - at both ends clear of the growth plate

We have taken the youngster very slowly in his brace for the first 2 months and I am delighted that he is now out of his brace and walking well with a very stable knee. We will obviously have to follow him up up closely and make sure that we don’t encounter any issues. Having gone below his growth plate on the femur and below his growth plate on his tibia with a relatively low position here there should be no issues there, but I will be taking long leg x-rays and laterals until he achieves skeletal maturity to continue to monitor him.

6 weeks post op PCL
6 weeks post op PCL

I was very happy with the way the surgery went and we were able to discharge our young patient after a day or two in hospital and we’re getting a customised brace to move this all forward.

Professor Adrian Wilson

LIVE PARENTAL ALLOGRAFT


This is the first paediatric PCL case using live parental donation in the UK and it seems to have gone very well.

The Tanner Scale

We use the Tanner scale as a measure of skeletal maturity. This patient was at the time of surgery a very small 11 year old – quite tiny for his age – and on the Tanner Scale he was at the lowest level, that is a Tanner 1, in terms of his development.

Parental allograft donation

The parental donation involves just making a 1cm incision over the hamstring insertion, and the hamstrings can be harvested in a few minutes. The recovery for the parent is really quick and in fact his father has done very well and the whole of this procedure only took about 15 minutes.

We got an excellent graft which we then fashioned and reinforced with tape and this was placed in an appropriate sterile container while we brought his young son into the operating theatre.

Technical details

Given that his growth plates were wide open our plan was to go below the growth plate on the femur and below the growth plate on the tibia, so actually way down the back of the tibia so I could avoid both. So if you look at the X-ray on the right you can see the tibia way out the back on the femur. On the side view in the X-ray on the left there is also some disruption and the knee isn’t properly lining up. That indicates that there was originally also a collateral ligament injury, but this did seem to heal during the time in the brace, leaving him with an isolated PCL problem.

If we then look at the pre-op MRI scans we can ACL is a little stretched and we just don’t see a very good image of the PCL and we see the growth plates wide open.

Preop mri of pcl disruption in child

MRI from the side - pre-operative - showing poor definition of the PCL at the back of the knee

For any surgeon-readers interested in more technical details, we did do some alignment views and some pre-op x-rays but I am not sure how useful they are. In terms of technique I used the Caliblator inserted into the knee and dissected down the back of the tibia with that. Positioning via a guide wire, I then brought in the paediatric guide and drilled a 3.5 mm tunnel well below the growth plate using a Flipcutter under direct vision.

Once the Flipcutter had gone I flipped the end of it and reversed the direction of drilling, creating a socket in the tibia. This allows the graft to be pulled through but using a socket rather than a tunnel preserves as much of the tibial bone as possible.

Post PCL reconstruction
Post op PCL in a child

So on the post-op x-ray you can see a front view with the tunnels both below the physis. Although the femoral button on the lateral view looks like it’s on the physis the actual main tunnel is below. The buttons appear also to be way off the bone, but in fact in small children the layer of tissue that you can’t see - the periosteum - is very thick and that’s why it appears that the buttons are sitting proud but in fact they are just sitting on the periosteum.

I am delighted that with the innovations in knee surgery that have developed over the last few years - many of which I have contributed to myself - we were able to pull off such a difficult procedure with such an excellent early outcome.

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