Diagnosing knee pain usually consists of a physical examination, as well as a careful look at your medical history.
How is knee pain diagnosed?
The various causes of knee pain can almost always be reliably diagnosed by an experienced musculoskeletal doctor or physiotherapist. To reach a diagnosis, a careful history of any previous pains or issues with joints is undertaken, as well as performing a physical examination
Most subtle onsets of knee pain in younger adults have their origins in the patellofemoral joint or soft tissue or tendons at the front of the knee. These diagnoses can be easily confirmed by careful physical inspection of these tissues and stressing them with resisted quadriceps tests.
Damage to the internal structures to the knee or the collateral ligaments have a history of trauma with immediate or slightly delayed swelling. Ligament special tests performed by a clinician are able to confirm this diagnosis on the basis of pain and/or increased movement when stressing these structures.
Degenerative knee osteoarthritis will be most commonly seen in middle aged or older individuals especially with a history of trauma to the knees. Typically, osteoarthritis can be seen with swelling, thickening to the knee joint margins and be felt with stiffness and pain when manipulating the knee in to extension and flexion.
Scans and tests
Depending on the findings from the history and examination, further diagnostic tests may be requested depending on the suspected diagnoses or to plan whether and what form of surgery may be offered.
X-rays are useful in determining whether there are any developmental or acquired alignment problems with the knee joints but more commonly are used to confirm the presence and severity of osteoarthritis.
An MRI scan may be requested to confirm cartilage and meniscal problems and also to image suspected ligament disruptions. In other cases of knee pain which has been resistant to physiotherapy, an MRI scan may also be requested.
What is knee cartilage pain?
The knee joint has two different forms of cartilage. The specialised bone found at the end of the thighbone (femur) and shinbone (tibia) which form the socket is known as hyaline cartilage. However, fibrous cartilage discs known as the menisci also lie within the inside and outside compartments of the knee joint. When clinicians refer to torn cartilage or cartilage pain, they are usually referring to a problem with the menisci.
Pain from a tear to the medial meniscus, which lies on the inside aspect of the knee, is normally felt as a focused pain in this area and sometimes at the back of the knee. Lateral meniscal tears often result in focal pain to the outer aspect of the knee. Lateral meniscal tears are far less common than medial meniscal tears.
The best treatment options for meniscal tears depend on several factors including the severity of the symptoms, an individual’s activity levels, the type and extent of the meniscal tear as well as whether the knee has any more widespread degenerative changes within it.
In general, young active patients who partake in sports involving impact work and rotation whose symptoms are preventing their return to sport, often do very well with keyhole operation to remove the torn cartilage or repair the cartilage. Older adults who have suffered a non-traumatic tear to their meniscus may be best served treating the problem with activity modification and physiotherapy strengthening exercises. An orthopaedic knee surgeon will be able to diagnose your knee problem and suggest the best treatment option for you.
What is anterior knee pain?
Anterior knee pain is a generic term used to describe pain at the front of the knee. The term is descriptive and relates to a number of different diagnoses. Diagnoses which come under the umbrella of anterior knee pain can usually be categorised into three sections.
Knee cap related pain, termed patellofemoral pain, encompasses the majority of cases of anterior knee pain. Patellofemoral pain is most often caused by weakness to the stabilising quadriceps muscles and poor flexibility to the muscles such as the hamstrings, quadriceps and iliotibial band. However, some individuals suffer with patellofemoral pain due to degenerative changes to the joint during middle and older age.
Some individuals do not get pain from the patellofemoral joint itself but get pain arising from the soft tissue to the inside and outside of the knee cap. The cause of this pain relates to poor biomechanical alignment which stretches the retinaculum leading to pain.
The third sub category within anterior knee pain relates to pain in the lower knee cap area. Pain is this area can relate to the patellar tendon or this tendon’s insertion to the patellar or tibia (shin bone). Alternatively, the pain can relate to inflammation of a structure known as Hoffa’s fat pad or fluid filled sacs known as the infrapatellar bursae.
If pain occurs at the front of the knee( behind the knee cap) and is generally worse on sitting for long periods of time, or on climbing stairs this is the likely diagnosis. Usually settles with rest, anti-inflammatories and ice packs. Exercises which strengthen the large muscles in the thigh are often helpful (e.g. lunges and squats)
Knee Osteoarthritis (Knee OA) This is an extremely common cause of knee pain and is caused by erosion or damage to the cartilage shock absorber of the knee with consequent pain. Pain is usually on weight bearing and gets gradual worse. It affects approximately eight million people in the UK. The knee is the joint most commonly affected by osteoarthritis.
Cartilage (meniscus) injury
Commonest in younger people ( <40). They are usually caused by sudden twisting movements on a weight bearing of the knee, resulting in pain, swelling and sometimes locking of the knee.
The cartilage shock absorbers, can become worn with general wear-and-tear and commonly cause pain in older individuals. Surgery is now only considered if there is a clear history of ‘locking’ of the knee. Evidence shows that surgery is NOT effective for uncomplicated knee pain in these cases.
In younger people they are usually caused by sudden twisting movements on a weight bearing of the knee, resulting in pain, swelling and sometimes locking of the knee.
Collateral Ligament Injury
The Collateral Ligaments (medial – inside of the knee and lateral- outside) connect the bones across the knee joint. These are usually injured during sudden twisting or changes of direction, often in contact sports such as football or rugby.
Urgent medical advice is needed if there is a significant injury with difficulty weight bearing and/or swelling.
In mild or moderate cases self-management may be effective –see above.
Cruciate Ligament injury ( anterior and posterior)
The cruciate ligaments, anterior and posterior, prevent forward and backward movement of the femur on the tibia respectively. Similar to collateral ligaments, they are injured during sudden trauma, usually in high velocity injuries such as rugby, skiing etc. It is a significant injury that requires clinical assessment. A joint swelling within 6 hours suggests bleeding in the joint and an urgent assessment via A&E is appropriate. Swelling arising over a longer period can be assessed more routinely. Difficulty with weight bearing also demands more urgent assessment.
This is generally a result of overuse, particularly from jumping-type or lunging activities, such as basketball or netball. It cause pain, at the front of the knee, in the patellar tendon which runs from the knee cap ( patellar) to the upper tibia.
Usually comes about after a minor injury, over activity or unusual activity, involving the knee. This should settle with self-management.
Can usually be prevented by warming up carefully before exercise, stretching to cool down afterwards, increasing activity levels slowly over time and ensuring you have supportive footwear.
Self-management options are often effective. Resuming activity with lower impact activities such as swimming and cycling will help strengthen muscles while avoiding recurrence.
Patellar dislocation or instability
Patella dislocation is usually obvious as the knee cap will become stuck to the side of knee. Pain will be severe and require an assessment at accident and emergency. Instability is however more common. In this situation the patellar feels as though it might dislocate but doesn’t and resumes its normal position. This is commoner in individuals who are female and hyperflexible. This condition is best managed by exercise advice from a physiotherapist.
Bursitis, or “housemaid’s knee”
This is caused by repetitive friction of the knee, from activities such as kneeling, resulting in a build-up of fluid over the knee, leading to pain and swelling at the front of the knee.
Usually responds well to self-management advice. Pain usually improves before the swelling, which can take longer to completely disappear.
If it becomes red or hot ,more painful or you feel unwell, clinician advice should be sought in case of potential infectionTreatments for knee pain