Lee Herrington qualified as a Chartered Physiotherapist in 1990 from Manchester University, United Kingdom, having previously completed a degree in Human Biology from Loughborough University. In 1996, he was awarded an MSc in Sports Injury and Therapy from Manchester Metropolitan University.
Lee is the lead clinician at the Knee-Rehab UK knee rehabilitation clinic and, amongst his many accolades, has worked with elite athletes for the last twelve years, including time with Great Britain Rugby League and Wigan Warriors Rugby League Club.
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One of Lee’s recently published articles was a systematic review of the use of the Hamstring tendon and the Patella tendon for use as a graft during Anterior Cruciate Ligament (ACL) surgery. We caught up with Lee to get the latest expert opinion on the Hamstring tendon versus the Patella tendon graft.
Hamstring vs Patella Tedon Graft Rehabilitation
What are the major differences in the rehabilitation of ACL reconstruction using Hamstring tendon and Patella tendon?
“In the early stages of rehabilitation, the programme for the two graft types will differ because of the differences in the nature of fixation that the operations are able to achieve. Because it has two bony fixation points, the Patella tendon graft is relatively more stable during the initial 6-8 weeks post surgery compared to the hamstring graft, which only has a single bony point of fixation. (W hen the Patella tendon graft is ‘harvested’ by the surgeon he takes the central third of the tendon, including its bony attachment to the knee cap and shin. For this reason the graft is referred to as Bone – Patella Tendon – Bone graft) .
“Because of this, greater care must be taken with hamstring graft patients to avoid pulling out of the graft from its non-osseous fixation point. This essentially means avoiding positions or activities which overly stress the graft, such as uncontrolled knee hyperextension (forced over straightening), valgus stresses (stresses on the inside of the knee, taking the knee into ‘knock knee’ position) on a flexed knee and unrestrained anterior Tibial translation (forward movement of the shin bone), most commonly from the pull of the quadriceps during open kinetic chain knee extension activities.
Note: Open Kinematic Chain refers to an exercise in which the involved limb is not fixed against a surface. For example, in the upper limb, a bicep curl is an open kinematic chain exercise, whereas a press up is a closed kinematic chain exercise.
“Open kinetic chain hamstring curls would obviously also have potentially deleterious effects on the donor site of Hamstring graft patients. The most frequent source of difference between early stage rehabilitation programmes for the two graft types is due to inter-surgeon variation, with some surgeons opting for 1-2 weeks immobilisation in an extension splint for hamstring grafts and unrestrained motion for Patella tendon.
“The key to rehabilitating either graft type is to establish normal motion at the knee and patellofemoral joint, reduce any swelling and muscle inhibition around the knee and regain normal motion control of the lower limb. Especially important is to control (and minimise) rotary and valgus loads at the knee in the early stage. Then to offer the patient individually tailored neuromuscular retraining programmes specific to the demands of their sport/lifestyle. This doesn’t just involve improving strength or static balance, but also dynamic control of the leg in progressively more stressful scenarios which eventual resemble the tasks required for sport”.
Effects of Removing Part of the Tendon
How can the patient function normally if either part of their Patella tendon or one of their Hamstring tendons is removed for use as an ACL graft?
“The answer to this question has to be based on perspective. In the short term (12-18 months following surgery), either graft site is likely not to be functioning normally. Lots of research shows these tissues are still weak at this stage. But all biological tissues have the ability to repair and re-grow if the stimulus is right. Players with these types of injury and surgical repair need to be rehabilitated over long periods not merely until they have returned to play, in order to maximise the potential functional return of the graft sites.
“Key to returning to normal function is the rehabilitation, rather than the surgery. The majority of studies indicate that regardless of the type of surgery, the outcome is good if the patient is compliant and follows a well-structured rehabilitation regime over a prolonged period.”
Don’t they get patellofemoral or hamstring problems?
“It is very rare to get Hamstring problems. In the review of literature we conducted it was rarely, if ever, a reported complication. Contrary to a popularly held belief, both types of operations get Patellofemoral joint pain (PFP). This is more a result of poor management of the things which cause PFP rather than of the type of surgery.
“PFP is caused by alteration in the stresses to which the patella and surrounding structures are exposed. There are two main causes of alteration of joint stresses. One cause is changes in the ‘dynamic Q angle’ (see note below), which is related to increased femoral medial rotation (turned in thighs), knee valgus (knock knees) and/or tibial lateral rotation (rolled out shins). These can of course be controlled if the patient is appropriately trained.
“The other main cause of PFP is weakness of the Quadriceps muscles. This means that the Patella is no longer pulled as deeply through the trochlear groove (of the thigh) during knee extension activities, so there is less joint surface contact and stresses per unit area are increased, leading to altered loading and pain. Failure to ameliorate Quadriceps inhibition (improve the weakness due to swelling or pain), will obviously facilitate the onset of this.”
Note: The Q-Angle refers to the ‘quadriceps angle’, which is a measurement of patellofemoral joint mechanics. The Q Angle is measured at the intersection of two lines: one drawn from a bony point at the front of the hip to the mid-point of the knee cap and the other from the mid-point of the knee cap to the insertion point for the Patella tendon, at the upper part of the shin. Research has shown that this Q Angle can be a reasonable estimate of the muscle force vectors (direction of muscle pull) over the patellofemoral joint. Further research has suggested that there is an increased risk of PFP if the Q Angle greatly exceeds 15 degrees.
Suitability of Hamstring and Patella Grafts
Would you say that one type of graft was more suitable for different patients – that is, it’s more suitable for different functional or lifestyle requirements?
“Our review, and a subsequent one, would indicate that the type of surgery does not affect outcome and it often comes down to personal choice and the expertise of the surgeon. Obvious things indicating a Hamstring graft over a Patella tendon graft include occupations involving kneeling as following a Patella tendon graft patients are rarely comfortable to kneel for any length of time. A second factor is appearance; some patients may not wish to have a scar on the anterior aspect of the knee for cosmetic reasons.”
Surgery vs Conservative Treatment
Is surgery always necessary following ACL rupture? How effective is conservative treatment?
“The question of whether surgery is necessary or not is somewhat of a contentious one. To date, no one has carried out appropriately balanced randomised controlled trials to answer this question. The commonest reason given for undertaking surgery is to reduce the risk of future joint degeneration. Interestingly, recent prospective surveys (e.g. Myklebust et al. 2003, American Journal of Sports Medicine) have shown that whether or not surgery is undertaken for ACL injury the joint degenerates significantly more than in uninjured players. The same study also showed that regardless of intervention the majority of patients returned to elite level sport.
“The other reason given for surgical repair is to stabilise the joint. It must be remembered that mechanically speaking, the ACL is an incredibly complex structure and the grafts used to reconstruct it are very poor substitutes for the original. They lack the multi-band nature of the original which gives it isometric strength throughout knee movement, creating tension in some part of the ligament through the whole range of knee movement. This not only provides stability but also proprioceptive feedback. This would appear to indicate that only if the patient is neuromuscularly re-trained will the joint have any hope of becoming functionally stable, regardless of whether or not it is operated on.
Numerous studies have shown that the ACL reconstructed, or ACL deficient, patients fail to have the longevity in sport of their peers and, as mentioned above, have considerably greater joint degradation. The challenge to those in sports rehabilitation is to rehabilitate these players in such a way that they can not only return to sport, but perform as well as before with a longevity to their careers comparative to their peers and without long-term joint damage. It is for the researchers in this field to identify those players who can adapt to ACL injury (with or without surgery) and return to an uncompromised sporting career and recognise those players whose injury is the precursor to long term joint degeneration and poor functional outcome.”