Causes of Knee Osteoarthritis – Symptoms, Treatment

Cartilage Changes in Aging[rx]

• Water content – decreased
• Collagen – same
• Proteoglycan content – decreased
• Proteoglycan synthesis – same
• Chondrocyte size – increased
• Chondrocyte number – decreased
• Modulus of elasticity – increased

Cartilage Changes in OA

• Water content – increased
• Collagen – disorganized
• Proteoglycan content – decreased
• Proteoglycan synthesis – increased
• Chondrocyte size – same
• Chondrocyte number – same
• Modulus of elasticity – decreased

Matrix Metalloproteases

Responsible for cartilage matrix degradation

• Stromelysin
• Plasmin
• Aggrecanase-1 (ADAMTS-4)
• Collagenase
• Gelatinase

Tissue inhibitors of MMPs

Control MMP activity preventing excess degradation

• TIMP-1
• TIMP-2
• Alpha-2-macroglobulin

The Symptom Of Osteoarthritis (OA) Of Knee

Diagnosis of Knee Osteoarthritis

Patients typically present to their healthcare provider with the chief complaint of knee pain. It is essential to obtain a detailed history of their symptoms. Pay careful attention to history as knee pain can be referred from the lumbar spine or the hip joint. It is equally important to obtain a detailed medical and surgical history to identify any risk factors associated with secondary knee OA.

The history of the present illness should include the following

• Onset of symptoms
• The specific location of pain
• Duration of pain and symptoms
• Characteristics of the pain
• Alleviating and aggravating factors
• Any radiation of pain
• The specific timing of symptoms
• Severity of symptoms
• The patient’s functional activity

Clinical Symptoms of Knee OA

Knee pain

• Typically of gradual onset
• Worse with prolonged activity
• Worse with repetitive bending or stairs
• Worse with inactivity
• Worsening over time
• Better with rest
• Better with ice or anti-inflammatory medication
• Knee stiffness
• Knee swelling
• Decreased ambulatory capacity

Physical examination of the knee should begin with a visual inspection. With the patient standing, look for periarticular erythema and swelling, quadriceps muscle atrophy, and varus or valgus deformities. Observe gait for signs of pain or abnormal motion of the knee joint that can be indicative of ligamentous instability. Inspect the surrounding skin for the presence and location of any scars from previous surgical procedures, overlying evidence of trauma, or any soft tissue lesions.

Range of motion (ROM) testing is a very important aspect of the knee exam. Active and passive ROM with regard to flexion and extension should be assessed and documented.

Palpation along the bony and soft tissue structures is an essential part of any knee exam. The palpatory exam can be broken down into the medial, midline, and lateral structures of the knee.

Areas of focus for the medial aspect of the knee

• Vastus medialis obliquus
• Superomedial pole patella
• The medial facet of the patella
• Origin of the medial collateral ligament (MCL)
• Midsubstance of the MCL
• Broad insertion of the MCL
• Medial joint line
• Medial meniscus
• Pes anserine tendons and bursa

Areas of focus for the midline of the knee

• Quadricep tendon
• Suprapatellar pouch
• Superior pole patella
• Patellar mobility
• Prepatellar bursa
• Patellar tendon
• Tibial tubercle

Areas of focus for the lateral aspect of the knee

• Iliotibial band
• Lateral facet patella
• Lateral collateral ligament (LCL)
• Lateral joint line
• Lateral meniscus
• Gerdy’s tubercle

A thorough neurovascular exam should be performed and documented. It is important to assess the strength of the quadriceps and hamstring muscles as these often times will become atrophied in the presence of knee pain. A sensory exam of the femoral, peroneal, and tibial nerve should be assessed as there may be concomitant neurogenic symptoms associated. Palpation of a popliteal, dorsalis pedis and the posterior tibial pulse is important as any abnormalities may raise the concern for vascular problems.

Other knee tests may be performed, depending on the clinical suspicion based on history

Special knee tests

• Patella apprehension – patellar instability
• J-sign – patellar maltracking
• Patella compression/grind – chondromalacia or patellofemoral arthritis
• Medial McMurray – a medial meniscus tear
• Lateral McMurray – lateral meniscus tear
• Thessaly test – a meniscus tear
• Lachman – anterior cruciate ligament (ACL) injury
• Anterior drawer – ACL injury
• Pivot shift – ACL injury
• Posterior drawer – posterior cruciate ligament (PCL) injury
• Posterior sag – PCL injury
• Quadriceps active test – PCL injury
• Valgus stress test – MCL injury
• Varus stress test – LCL injury

Radiographic Findings of OA

• Joint space narrowing
• Osteophyte formation
• Subchondral sclerosis
• Subchondral cysts

Differential Diagnosis

Any potential cause of local or diffuse knee pain should be considered in the differential diagnosis of knee osteoarthritis.

• Hip arthritis
• Low back pain
• Spinal stenosis
• Patellofemoral syndrome
• Meniscal tear
• Pes anserine bursitis
• Infections arthritis
• Gout
• Pseudogout
• Iliotibial band syndrome
• Collateral or cruciate ligament injury

Treatment of Knee Osteoarthritis

Treatment for knee osteoarthritis can be broken down into non-surgical and surgical management. Initial treatment begins with non-surgical modalities and moves to surgical treatment once the non-surgical methods are no longer effective. A wide range of non-surgical modalities is available for the treatment of knee osteoarthritis. These interventions do not alter the underlying disease process, but they may substantially diminish pain and disability.[rx][rx][rx]

Non-Surgical Treatment Options[rx]

• Patient education
• Activity modification
• Physical therapy
• Weight loss
• Knee bracing
• Acetaminophen
• Nonsteroidal anti-inflammatory drugs (NSAIDs)
• COX-2 inhibitors
• Glucosamine and chondroitin sulfate
• Corticosteroid injections
• Hyaluronic acid (HA)

The first-line treatment for all patients with symptomatic knee osteoarthritis includes patient education and physical therapy. A combination of supervised exercises and a home exercise program have been shown to have the best results. These benefits are lost after 6 months if the exercises are stopped.

The American Academy of Orthopedic Surgeons (AAOS) recommends this treatment.

• Weight loss – is valuable in all stages of knee osteoarthritis. It is indicated in patients with symptomatic arthritis with a body mass index greater than 25. The best recommendation to achieve weight loss is with diet control and low-impact aerobic exercise. There is moderate evidence for weight loss based on the AAOS guidelines.
• Knee bracing – in the setting of osteoarthritis includes unloader-type braces which shift the load away from the involved knee compartment. This may be useful in the setting where either the lateral or medial compartment of the knee is involved such as in a valgus or varus deformity.
• Immobilization – Your doctor may recommend that your child wear a brace for 3 to 4 weeks. This stabilizes the knee while it heals.
• Weightbearing –  Because putting weight on the knee may cause pain and slow the healing process, your doctor may recommend using crutches for the first week or two after the injury.
• Physical therapy – Once the knee has started to heal, your child’s doctor will recommend physical therapy to help your child regain normal motion. Specific exercises will strengthen the thigh muscles holding the knee joint in place. Your child’s commitment to the exercise program is important for a successful recovery. Typically, children return to activity 3 to 6 weeks after the injury.
• Emergent closed reduction followed by vascular assessment/consult – indications to considered an orthopedic emergency, vascular consult indicated if pulses are absent or diminished following reduction if arterial injury confirmed by arterial duplex ultrasound or CT angiography
• Immobilization as definitive management – successful closed reduction without vascular compromise, most cases require some form of surgical stabilization following reduction, outcomes of worse outcomes are seen with nonoperative management/prolonged immobilization will lead to loss of ROM with persistent instability.
• Rest Your Leg – Once you’re discharged from the hospital in a legislating, your top priority is to rest your and not further inflame the injury. Of course, the arm sling not only provides support, but it also restricts movement, which is why you should keep it on even during sleep. Avoiding the temptation to move your will help the bone mend quicker and the pain fades away sooner.

Medication

• Antibiotic – Cefuroxime or Azithromycin, or  Flucloxacillin or any others cephalosporin/quinolone antibiotic must be used to prevent infection or clotted blood remove to prevent furthers swelling and edema.
• NSAIDs – Prescription-strength drugs that reduce both pain and inflammation. Pain medicines and anti-inflammatory drugs help to relieve pain and stiffness, allowing for increased mobility and exercise. There are many common over-the-counter medicines called non-steroidal anti-inflammatory drugs (NSAIDs). They include and Ketorolac, Aceclofenac, Naproxen, Etoricoxib.
• Corticosteroids – Also known as oral steroids, these medications reduce inflammation.
• Muscle Relaxants –  These medications provide relief from associated muscle spasms.
• Neuropathic Agents – Drugs(pregabalin & gabapentin) that address neuropathic—or nerve-related—pain. This includes burning, numbness, and tingling.
• Opioids – Also known as narcotics, these medications are intense pain relievers that should only be used under a doctor’s careful supervision.
• Topical Medications – These prescription-strength creams, gels, ointments, patches, and sprays help relieve pain and inflammation through the skin.
• Calcium & vitamin D3 – to improve bone health and healing fracture. As a general rule, men and women age 50 and older should consume 1,200 milligrams of calcium a day, and 600 international units of vitamin D a day.
• Dietary supplement-to remove general weakness & improved health.
• Antidepressants – A drug that blocks pain messages from your brain and boosts the effects of endorphins (your body’s natural painkillers).
• Glucosamine & Diacerein, Chondroitin sulfate – can be used to tightening the loose tension, cartilage, ligament, and cartilage, ligament regenerate cartilage or inhabit the further degeneration of cartilage, ligament. They are structural components of articular cartilage, and the thought is that a supplement will aid in the health of articular cartilage. No strong evidence exists that these supplements are beneficial in knee OA; in fact, there is strong evidence against the use according to the AAOS guidelines. There are no major downsides to taking the supplement. If the patient understands the evidence behind these supplements and is willing to try the supplement, it is a relatively safe option. Any benefit gained from supplementation is likely due to a placebo effect.
• Intra-articular corticosteroid injections – may be useful for symptomatic knee osteoarthritis, especially where there is a considerable inflammatory component. The delivery of the corticosteroid directly into the knee may reduce local inflammation associated with osteoarthritis and minimize the systemic effects of the steroid.
• Intra-articular hyaluronic acid injections (HA) – injections are another injectable option for knee osteoarthritis. HA is a glycosaminoglycan that is found throughout the human body and is an important component of synovial fluid and articular cartilage. HA breaks down during the process of osteoarthritis and contributes to the loss of articular cartilage as well as stiffness and pain. Local delivery of HA into the joint acts as a lubricant and may help increase the natural production of HA in the joint.

Glucosamine With or Without Chondroitin or Chondroitin Alone

Seven studies that assessed the effects of glucosamine, chondroitin, or the combination met inclusion criteria. No studies addressed short-term outcomes of glucosamine combined with chondroitin, and no studies addressed the short- or medium-term effects of glucosamine alone.

Strength or Resistance Training

Ten studies that assessed strength or resistance training met inclusion criteria.

Agility Training

Eight RCTs that assessed the effects of agility training met inclusion criteria.

Aerobic Exercise

Five RCTs that assessed the effects of aerobic exercise met inclusion criteria.

General Exercise Therapy

Six interventions that combined exercise interventions and did not fit predefined categories were identified.^[rx–rx]

Tai Chi

Three RCTs that met inclusion criteria assessed the effects of tai chi compared with resistance training or no activity. ^{rx, rx]}

Yoga

One RCT that met inclusion criteria assessed the short-term effects of yoga.^[rx]

Manual Therapy (Including Massage and Acupressure)

Nine RCTs that assessed the effects of manual therapy (including massage, self-massage, and acupressure) met inclusion criteria.^{[rx, rx, rx–rx]}

Balneotherapy and Mud Treatment

• Four RCTs that met inclusion criteria assessed the effects of balneotherapy, mud baths, or topical mud.^[rx–rx] No studies of balneotherapy assessed short- or long-term outcomes.
• Balneotherapy had a beneficial effect on medium-term function, and a beneficial, but the inconsistent effect on medium-term pain across two single-blind RCTs (low strength of evidence). No studies assessed the effects of balneotherapy on short- or long-term outcomes.
• Evidence was insufficient for an effect of mud (mud baths or topical mud) on short-term outcomes.

Heat, Infrared, and Therapeutic Ultrasound

One RCT that assessed the effects of heat,one that assessed the effects of infrared, and three that assessed the effects of pulsed and continuous U/S on outcomes of interest met inclusion criteria.^[rx–rx] Only short-term effects were reported for heat and infrared, and no medium-term effects were reported for any of the interventions.

TENS and NMES

Four RCTs that compared the effects of TENS with those of sham-TENS^[rx–rx] and five RCTs that assessed the effects of NMES met inclusion criteria.^{[rx, rx–rx]} No studies were identified that assessed long-term outcomes.

Pulsed Electromagnetic Field (PEMF)

Three RCTs that assessed short-term effects of PEMF on pain met inclusion criteria.^[rx–rx] No RCTs were identified that assessed medium- or long-term outcomes of PEMF.

Whole-Body Vibration (WBV)

Seven RCTs that met the inclusion criteria assessed the effects of WBV on outcomes of interest.^[rx–rx] No studies that assessed long-term effects were identified.

Orthoses (Knee Braces, Shoe Inserts, Custom Shoes)

Three RCTs on knee braces eight RCTs on shoe inserts, four RCTs on footwear,^[rx–rx] and one RCT on cane use met the inclusion criteria. No RCTs on the short-term effects of footwear were identified.

Weight Loss

Five RCTs and five single-arm trials (reported in six publications)^[rx–rx] that assessed the effects of weight loss on OA met inclusion criteria.

Surgical Treatment Options[rx]

Open Reduction

• irreducible knee
• posterolateral dislocation
• open fracture-dislocation
• obesity (may be difficult to obtain closed)
• vascular injury

External Fixation

• vascular repair (takes precedence)
• open fracture-dislocation
• compartment syndrome
• obese (if difficult to maintain reduction)
• polytrauma patient

Delayed Ligamentous Reconstruction/Repair

• instability will require some kind of ligamentous repair or fixation
• patients can be placed in a knee immobilizer until treated operatively
• improved outcomes with early treatment (within 3 weeks)

Arthroscopy +/- Open Debridement

• Arthroscopic or open debridement with removal of any loose bodies may be necessary for displaced osteochondral fractures or loose bodies.

MPFL Re-Attachment Or Reconstruction (Proximal Realignment)

• Proximal realignment constitutes the reconstruction of the MPFL. In brief, to repair the ligament, a longitudinal incision is made at the border of the VMO, just anterior to the medial epicondyle. The ligament is usually re-attached to the femur using bone anchors. If the patient has had recurrent dislocations, then reconstruction may be necessary by harvesting gracilis or semitendinosus which are then attached to the patella and femur.
• Isolated repair/reconstruction of the MPFL is not a recommendation in those with bony abnormalities including TT-TG distance greater than 20mm, convex trochlear dysplasia, severe patella alta, advanced cartilage degeneration or severe femoral anteversion.[rx]

Lateral Release (Distal Realignment)

• A lateral release cuts the retinaculum on the lateral aspect of the knee joint. The aim is to improve the alignment of the patella by reducing the lateral pull.

Osteotomy (Distal Realignment)

• Where there is abnormal anatomy contributing to poor patella tracking and a high TT-TG distance, the alignment correction can be through an osteotomy. The most common procedure of this type is known as the Fulkerson-type osteotomy and involves an osteotomy as well as removing the small portion of bone to which the tendon attaches and repositioning it in a more anteromedial position on the tibia.

Trochleoplasty

• Trochleoplasty is indicated in recurrent dislocators with a convex or flat trochlea. The trochlear groove is deepened to create a groove for the patella to glide through; this may take place alongside an MPFL reconstruction. Studies suggest it is not advisable in those with open growth plates or severely degenerative joints. This procedure is uncommon except in refractory cases.

High Tibial Osteotomy (HTO)

• Osteotomy
• Unicompartmental knee arthroplasty (UKA)
• Total knee arthroplasty (TKA)

A high tibial osteotomy (HTO) may be indicated for unicompartmental knee osteoarthritis associated with malalignment. Typically an HTO is done for varus deformities where the medial compartment of the knee is worn and arthritic. The ideal patient for an HTO would be a young, active patient in whom arthroplasty would fail due to excessive component wear. An HTO preserves the actual knee joint, including the cruciate ligaments, and allows the patient to return to high-impact activities once healed. It does require additional healing time compared to an arthroplasty, is more prone to complications, depends on bone and fracture healing, is less reliable for pain relief, and ultimately does not replace cartilage that is already lost or repair any remaining cartilage. An osteotomy will delay the need for arthroplasty for up to 10 years.

Indications for HTO

• Young (less than 50 years old), active patient
• Healthy patient with good vascular status
• Non-obese patients
• Pain and disability interfering with daily life
• Only one knee compartment is affected
• A compliant patient who will be able to follow the postoperative protocol

Contraindications for HTO

• Inflammatory arthritis
• Obese patients
• Knee flexion contracture greater than 15 degrees
• Knee flexion less than 90 degrees
• If the procedure will need greater than 20 degrees of deformity correction
• Patellofemoral arthritis
• Ligamentous instability

A UKA also is indicated in unicompartmental knee osteoarthritis. It is an alternative to an HTO and a TKA. It is indicated for older patients, typically 60 years or older, and relatively thin patients; although, with newer surgical techniques the indications are being pushed.

Indications for UKA

• Older (60 years or older), lower demand patients
• Relatively thin patients

Contraindications for UKA

• Inflammatory arthritis
• ACL deficiency
• Fixed varus deformity greater than 10 degrees
• Fixed valgus deformity greater than 5 degrees
• Arc of motion less than 90 degrees
• Flexion contracture greater than 10 degrees
• Arthritis is more than one compartment
• Younger, higher activity patients or heavy laborers
• Patellofemoral arthritis

A TKA is the surgical treatment option for patients failing conservative management and those with osteoarthritis in more than one compartment. It is regarded as a valuable intervention for patients who have severe daily pain along with radiographic evidence of knee osteoarthritis.

Indications for TKA

• Symptomatic knee OA in more than one compartment
• Failed non-surgical treatment options

Contraindications for TKA

Absolute

• Active or latent knee infection
• Presence of active infection elsewhere in the body
• Incompetent quadriceps muscle or extensor mechanism

Relative

• Neuropathic arthropathy
• Poor soft-tissue coverage
• Morbid obesity
• Noncompliance due to major psychiatric disorder or alcohol or drug abuse
• Insufficient bone stock for reconstruction
• Poor health or presence of comorbidities that make the patient an unsuitable candidate for major surgery and anesthesia
• Patient’s poor motivation or unrealistic expectations
• Severe peripheral vascular disease

Advantages of UKA vs TKA

• Faster rehabilitation and quicker recovery
• Less blood loss
• Less morbidity
• Less expensive
• Preservation of normal kinematics
• Smaller incision
• Less post-surgical pain and shorter hospital stay

Advantages of UKA vs HTO

• Faster rehabilitation and quicker recovery
• Improved cosmesis
• The higher initial success rate
• Fewer short-term complications
• Lasts longer
• Easier to convert to TKA

Complications of Knee Osteoarthritis

Complications associated with non-surgical treatment are largely associated with NSAID use.

Common Adverse Effects of NSAID Use

• Stomach pain and heartburn
• Stomach ulcers
• A tendency to bleed, especially while taking aspirin
• Kidney problems

Common Adverse Effects of Intra-Articular Corticosteroid Injection

• Pain and swelling (cortisone flare)
• Skin discoloration at the site of injection
• Elevated blood sugar
• Infection
• Allergic reaction

Common Adverse Effects of Intra-Articular HA Injection

• Injection site pain
• Muscle pain
• Trouble walking
• Fever
• Chills
• Headache

Complications Associated with HTO

• Recurrence of deformity
• Loss of posterior tibial slope
• Patella baja
• Compartment syndrome
• Peroneal nerve palsy
• Malunion or nonunion
• Infection
• Persistent pain
• Blood clot

Complications Associated with UKA

• Stress fracture of the tibia
• Tibial component collapse
• Infection
• Osteolysis
• Persistent pain
• Neurovascular injury
• Blood clot

Complications Associated with TKA

• Infection
• Instability
• Osteolysis
• Neurovascular injury
• Fracture
• Extensor mechanism rupture
• Patellar maltracking
• Patellar clunk syndrome
• Stiffness
• Peroneal nerve palsy
• Wound complications
• Heterotopic ossification
• Blood clot

References