A tear of a cruciate ligament will represent a major injury to any patient. This multi-page Primer highlights the key issues.

Page updated July 2023 by Dr Sheila Strover (Clinical Editor)


Generally in good hands cruciate ligament reconstruction is highly successful, but major complications may occur.


Recipient site complications

At the recipient site (where the new graft is positioned) complications of cruciate surgery can include:


graft rupture

Rupture of the graft may occur secondary to poor positioning, overgrowth of the bony notch through which the graft passes or aggressive rehabilitation too early, before the new blood supply has grown in and the tendon fibres have regained strength.

cyclops lesion

A cyclops lesion is a lumpy obstruction in the joint, limiting range of movement, and due to excessive scar tissue in the notch.

loosening of the fixation device

Fixation devices may become loose at the femoral or tibial bone shaft or in the tunnels.

incorrect graft tensioning

It is essential that the surgeon has skill in measuring and 'tensioning' the graft, to ensure that it is exactly the right length when put under stress.


Excessive scar tissue in the joint leading to knee stiffness.


Infection within the knee is a serious problem needing urgent attention.

Failure of Anterior Cruciate Ligament Reconstruction. Samitier G, Marcano AI, Alentorn-Geli E, Cugat R, Farmer KW and Moser MW. Arch Bone Jt Surg. 2015 Oct; 3(4): 220–240.

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Donor site complications

At the donor site (where the graft material has been 'harvested' from) complications can include:

patellar fracture

Fracture (break) of the kneecap when patellar tendon is used as the graft material.


hernia at the site of a hamstrings harvest

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Complications remote from either recipient or donor site

Remote from recipient or donor site complications can include:


Scarring in and around the knee joint, leading to a stiff knee and patellar problems (patella infers (baja) and pain.

Of all the conditions on the list for triggering arthrofibrosis, anterior cruciate ligament surgery used to come tops, but the chance of developing arthrofibrosis after ACL surgery is less nowadays than it used to be. This is because research into this problem led to surgeons changing their practice, so that one is less likely these days to have an ACL reconstruction complicated by arthrofibrosis than one would have ten years ago.

compartment syndrome

Where irrigation of the joint with fluid under pressure leads to tracking of the fluid into the calf with tense swelling.


Haemarthrosis is bleeding into the joint space

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History of cruciate ligament reconstruction

With the advent in the 1980s of synthetic ligament materials and new surgical instrumentation, surgeons offered the first real hope of full restoration of function to patients with torn cruciates. With synthetic ligament surgery there came a big push to educate surgeons in the new surgical techniques, and an increase in the number of patients having cruciate reconstruction followed. It was not long, however, before synthetic ligaments went out of fashion, partly because they had inherent problems of their own and partly because the new techniques advanced to allow fully biological 'autograft' (the patient's own tissue) to be used as a graft material. Of the autografts, the patellar-tendon-graft (PTG) was promoted as 'the gold standard' and surgeons all over the world started to perform PTG cruciate reconstruction surgery.

As the technique shifted from the synthetic graft to the natural graft, which required ingrowth of blood vessels and the formation of new ligament cells, so the surgeons tended to 'protect' the graft by immobilising the patient's knee for a fairly prolonged period of time. Rehab was progressed cautiously. But the outcome was not always as good as expected, and an increasing number of post-surgery cruciate ligament patients started having trouble regaining full range of motion.


As these patients started in the 1990s being referred to specialist units for assessment and management, leaders in the field began to publish their findings (ref 2) - and they pointed out that many of these joints were being limited by the presence of scar tissue within the joint cavity.


Research was undertaken to find out why, and two of the main reasons were shown to be the timing of the reconstruction surgery after the initial injury and the length of the period of immobilisation after surgery (ref 3). This led to a change of practice amongst surgeons that has resulted in a fall in the percentage of cruciate patients progressing to arthrofibrosis - 

  • the initial surgery is generally delayed for about 3 weeks after injury, and surgery is not undertaken until full range of motion is restored and the joint is not inflamed 
  • the period of immobilisation was decreased and patients were put through an accelerated rehabilitation programme.

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