Participating in sports and physical activities is great for both our physical and mental health. In 2023, around 63.5% of the UK population aged over 16 regularly participated in sport (www.statista.com), with football, rugby, golf and tennis being some of the most popular sports. Approximately 40% of adult males and 30% of adult females in England take part in sports on a weekly basis (Sport England). This is welcome and to be encouraged, however, the downside is sporting injuries. Often these are knocks and twinges that will recover quickly but sometimes more serious damage is done, and surgery may be advised. In this article I am going to discuss the most common sporting injuries that occur in the knee, and my approach to treating them.
Let’s take a look at the knee then
So, common sporting injuries to the knee can involve the ligaments, the meniscal cartilage or articular cartilage, which is the cartilage that lines the knee joint surfaces. Treatment for knee injury can range from injections, physiotherapy and surgical intervention and of course, surgical intervention. Medical opinion should always be sought following injury that results in swelling (caused by excess synovial fluid accumulating around. The knee joint), locking, giving way or pain and an inability to bear weight. An accurate diagnosis of ten requires X rays and / or MRI scans.
What are the most common knee sporting injuries?
Anterior Cruciate Ligament (ACL) Tear
The most common knee ligament injury is a tear to the anterior cruciate ligament (ACL). The ACL connects the thigh bone to the shin bone and keeps the knee stable.
There is often a history to this injury such as sudden stops, jumps, or directional changes. Patients often give a history of immediate swelling and needing to be carried off the pitch. The diagnosis for this type of injury is confirmed by clinical examination and relevant imaging such as MRI scan.
Treatment options
- Conservative treatment can be tried initially such as rehabilitation, bracing and/or activity modification. Often ACL injuries will stabilise after physiotherapy, however, more frequently surgery will be required.
- Surgical reconstruction.
If there are ongoing instability issues then surgery will be necessary. Reconstructive surgery for an ACL tear often leads to a good outcome in respect of knee stability (Tegner activity score). Also, if there is an accompanying meniscal tear requiring repair then surgery may also be advisable to protect the repair. So, it is very important to understand that a personalised approach is required as it is not one size fits all.
Role of Prehabilitation in surgery to the knee
There is some evidence that targeted prehabilitation using progressive strengthening and neuromuscular training for at least 6 weeks prior to surgery results in better functional outcomes for up to two years after surgery and higher percentages of return to pre-injury sport levels. So, it is always worthwhile engaging with a physiotherapy program irrespective of whether surgery is planned or not.
Graft options
In ACL reconstruction surgery the damaged ligament can be replaced using a graft. A number of different tissues can be used to replace the ACL. If the tissue is taken from your own body, this is called an autograft graft. Tissue taken from a donor is called an allograft.
a) Autograft - tissues that can be used are part of the hamstring tendon, patellar tendon or quadriceps tendon. The first two are the most commonly used grafts in the UK. However, there is an element of robbing from Peter to pay Paul with minor downsides related to this.
b) Allograft (processed grafts from donor) - there is a 25% incidence of re-rupture in the young but this is not seen in older population (over 35-40 years). This is popular in the USA and useful in revision scenarios and with slightly older patients.
c) Artificial synthetic graft - This is a tubular structure that replaces the torn ligament. Some questions do remain about the very long term results, although materials are improving.
I prefer to have a full discussion of the pros and cons of the various graft options with my patients before deciding the best options for their individual needs.
Timing of surgery – no consensus
It was initially thought that surgery on the knee for ACL tear within 6 weeks of the injury would lead to arthrofibrosis, which is where scar tissue prevents normal knee function. However, there is some evidence that with newer surgical techniques knees that are not too inflamed and that have a reasonable range of movement can be operated on earlier.
In fact, there is some evidence that delaying surgery for more than 6 months can result in a four times increase in medial meniscus tears.
Rehabilitation duration and return to sports
The one thing that my patients always want to know is how quickly they will be able to return to participating in sport after their knee surgery.
We use the Limb Symmetry Index (LSI) to determine any discrepancy between the legs in terms of strength, function and mobility following ACL reconstruction. A LSI score of more than 90% (in both strength and specialised hop tests) is often used as a benchmark for return to play following ACL reconstruction. Unfortunately this is rarely achieved before 12 months. Indeed, one study of 150 young patients showed those who returned to sport before nine months had a statistically significantly higher rate of second ACL injury.
Meniscus tear
Another very common knee injury is a meniscus tear. Which is tearing of the cartilage that cushions the knee joint.
Surgery to repair a meniscus tear can be either:
- Meniscectomy: Removal of the torn portion, or
- Meniscus repair: Suturing the tear; more common in younger patients and athletes- the more meniscus you take out the more likely you are to develop arthritis. However, not all types of tear are amenable to repair and a repair does not always work as the meniscus has a rather tenuous blood supply.
Diagnosis for this type of knee injury is confirmed by history, physical examination and imaging (MRI).
Conservative treatment would be in the form of low impact exercises (straight leg raises with and without weights, cross training, exercise biking and swimming, doing either freestyle or backstroke – not breastroke!), physiotherapy and steroid injections for pain relief.
Sometimes a procedure called arthroscopy is needed to diagnose the knee injury properly. This is a minimally invasive surgical procedure that involves insering a camera to look inside the knee to see what damage has occurred. A locked knee with meniscal injury (when it is stuck) requires urgent arthroscopic intervention. However, arthroscopy for meniscus injury can be linked to arthritis.
Articular Cartilage Injuries (Chondral Defects)
Sometimes the articular cartilage on the ends of bones can also be damaged.
Surgical approaches to repair articular cartilage injuries are as follows:
- Acute Injury- If caught early and the detached cartilage fragment is intact, it can be reattached successfully, especially in young people.
- Chronic Injury- this is a more difficult situation as evidenced by the different techniques available. These techniques include the following:
Microfracture
The aim of this is to stimulate growth of new cartilage by creating small holes in the bone. This results in blood and bone marrow rich in growth factors seeping out and forming a layer of fibrocartilage. This is possible in smaller size defects only.
OATS (Osteochondral Autograft Transfer System)
This involves transfering healthy cartilage from another area.
Autologous Chondrocyte Implantation (ACI)
This is where laboratory-grown cartilage stem cells are implanted into the defect. This is a two-stage procedure that can only be done in highly specialised centres and is not easily available.
BMAC (Bone Marrow Aspirate Concentrate)
BMAC is called "biologic" therapy as it used the body's own cells to promote healing. The procedure involves extracting bone marrow, concentrating the stem cells and growth factors and injecting them back into the damaged area of the knee. This is used for single stage procedures with various synthetic cartilage scaffold substitutes.
Getting back into sport
The recovery process following these procedures and based on the location of the defects, may require up to 6 weeks of protected weight bearing and bracing, followed by intensive physiotherapy.
