C is a professional footballer. In January 2017 he suffered a meniscal tear to his left knee whilst training. That was treated by D who is a specialist knee surgeon. The operation appeared to go well. The meniscal tear healed. Unfortunately, his knee subsequently showed signs of infection. On 9 March 2017 after some blood tests were taken he was advised to have urgent surgery to remove the infective material in his left knee. That surgery was also undertaken by the Defendant. The operation took place on 17 March 2017. 
This claim concerns the treatment he received on that day. It is C’s case that in the course of that surgery, described by D as an ‘aggressive’ procedure to remove infective material from the knee joint to prevent the development of septicaemia, iatrogenic damage was negligently caused to the tendon that crosses the knee joint on the medial side of the patellar. That tendon is known anatomically as the medial retinaculum. Its function is to hold the patellar in place. 
It was D’s case that no damage occurred during surgery on 17 March 2017, but rather that the damage occurred subsequent to surgery and probably after an ultrasound scan on 27 March 2017. D’s case was that the burden of proof lies on C and while he does not have to prove anything, other explanations offered by him or his expert Mr Anand, for example, that the rupture was due to infection, failure to follow post-operative instructions, of multifactorial origin, or evolved gradually, were entirely plausible causal mechanisms. 
the sole issue which I am asked to determine in this case is: whether D caused a large rupture or defect in the medial retinaculum of C’s left knee on 17 March 2017 in the course of surgery (a synovectomy procedure to remove infected material from the knee). 
In summary, the evidence adduced by C and his expert has not been sufficiently cogent or compelling to allow me to conclude on the balance of probabilities that D caused a 3cm diameter defect to C’s medial retinaculum on 17 March 2017 in the course of the synovectomy procedure. 
the claim has not been proved on the balance of probabilities and for that reason the claim must be dismissed.