Congenital malformations, deformities, and chromosomal abnormalities (Q00-Q99).
- Congenital knee dislocation (bes. common in neurologic disorders (e.g., arthrogrypnosis, myelodysplasia, Ehlers-Danlos syndrome) [infants/toddlers].
- Congenital patellar luxation – slipping of the patella out of the femoral sliding bearing (usually laterally) [growth phase; infants/adolescents].
- Disc meniscus (anatomical variant of the menisci of the knee joint) [infants/toddlers].
But, blood-forming organs – immune system (D50-D90).
- Childhood obesity (overweight).
- Hemophilia (hemophilia) → hemarthrosis /joint degeneration.
Endocrine, nutritional and metabolic diseases (E00-E90).
- Hemochromatosis (iron storage disease) – genetic disease with autosomal recessive inheritance with increased deposition of iron as a result of increased iron concentration in the blood with tissue damage.
Musculoskeletal system and connective tissue (M00-M99).
- Osteoarthritis – gonarthrosis (knee joint osteoarthritis) [middle-aged and elderly patients].
- Arthritis (joint inflammation), usually as monarthritis (limited to a single joint (= mon[o]articular) joint inflammation) [infants/toddlers]
- Baker’s cyst (popliteal: belonging to the popliteal fossa); popliteal cyst) – cysts usually become symptomatic only between the 20th and 40th year of life; but can also be observed in the 1st decade of life; symptomatology: feeling of pressure in the area of the popliteal fossa with occasional radiation into the calf
- Ligament lesion – ligament injury, unspecified.
- Bursitis (bursitis); symptomatology: swelling and tenderness and pain on movement [middle-aged and elderly patients].
- Chondrocalcinosis (synonym: pseudogout); gout-like disease of the joints caused by deposition of calcium pyrophosphate in cartilage and other tissues; leads, among other things, to joint degeneration (often of the knee joint); symptomatology resembles an acute attack of gout → joint degeneration [middle age and older patients].
- Chondromalacia patellae (“cartilage disease of the kneecap”) – degeneration or softening of the cartilaginous posterior surface of the kneecap [adolescents/young adults]
- Epiphyseal detachment (epiphysiolysis capitis femoris); usually non-traumatic slippage of the femoral head epiphysis from the neck of the femur during puberty; symptomatology: hip and knee complaints [infants/toddlers].
- Functional knee pain
- Ganglion – benign neoplasm arising from the tendon sheaths, tendons or joint capsule.
- Joint mouse (mobile foreign body in the joint capsule).
- Gout (arthritis urica/uric acid-related joint inflammation or tophic gout)/hyperuricemia (increase in uric acid levels in the blood) → joint degeneration.
- Infectious arthritis (inflammation of the joints).
- Cruciate ligament rupture [adolescents/young adults]
- Lateral disc meniscus
- Lyme arthritis – bacterial joint inflammation (arthritis) that can occur after inadequate therapy in the 3rd stage of Lyme disease.
- Meniscal ganglion – cyst filled with fluid or a jelly-like substance directly adjacent to a knee joint meniscus [middle-aged and elderly patients].
- Meniscal lesion – meniscal injury, unspecified.
- Meniscal tear [adolescent/young adult]
- Degenerative meniscal tear [middle-aged and older patients].
- Ahlbäck’s disease – aseptic bone necrosis, i.e. not caused by infection [middle age and elderly patients].
- Osgood-Schlatter disease (synonyms: osteochondrosis deformans juvenilis of the tibial tuberosity, apophysitis tibialis adolescentium; Engl. Osgood Schlatter disease, rugby knee) – painful irritation of the insertion (attachment) of the patellar tendon (patella tendon) on the anterior tibia, which can lead to aseptic necrosis (tissue death in the absence of infection) of the tibial apophysis (area of the. Growth joint of the tibia bone) in children and adolescents come; occurs mainly in boys; Symptomatology: discrete rest pain and increased load pain in the area of the tibial tuberosity (rough bone process (apophysis) at the proximal end of the anterior edge of the tibia), which occurs bes. when climbing stairs and after sports activity (jumping disciplines, soccer) increased [adolescents / young adults].
- Paget’s disease – disease of the skeletal system with bone remodeling.
- Mobus Perthes – Aseptic necrosis of the femoral head (death of part of the bony head of the femur), which occurs in childhood childhood disease. It is caused by ischemia (impaired blood flow) and necrosis (death) of bone tissue in the femoral head. Symptoms: Gonalgia (knee pain), go-slow limp, and hip joint rotation restrictions [adolescents/young adults].
- Reiter’s disease (synonyms: Reiter’s syndrome, Reiter’s disease, urethro-oculo-synovial syndrome, arthritis dysentericá, postenteritis reactive arthritis, sexually acquired reactive arthritis (SARA), undifferentiated oligoarthritis) – seronegative spondyloarthropathy caused by intestinal or urinary tract disease with bacteria (usually chlamydia), especially in HLA-B27 positive individuals. It can manifest as arthritis (joint inflammation), conjunctivitis (conjunctivitis), urethritis (urethritis) and partly with typical skin changes.
- Larsen-Johansson disease (synonym: Sinding-Larsen-Johansson disease); painful inflammatory reaction of the origin of the patellar tendon (patellar tendon) at the tip of the kneecap. This can cause a piece of bone to detach from the patella and necrotize (die). The disease occurs mainly in adolescents and belongs to the group of osteonecrosis.
- Osteochondrosis dissecans – circumscribed aseptic bone necrosis below the articular cartilage, which can end with the rejection of the affected bone area with the overlying cartilage as a free joint body (joint mouse); this often causes irritation; Symptomatology: joint blockages with pain; pain that occurs bes. with loads on the knee joint and typically diminish at rest; occurs predominantly towards the end of the growth age [adolescents / young adults].
- Osteomyelitis (bone marrow inflammation) [infants/toddlers]
- Osteonecrosis (circumscribed cartilage tissue damage to femoral condyle/thigh rolls, tibial plateau/top surface of tibia, or patella/patella).
- Patellar dysplasia (malformation of the kneecap).
- Patellar luxation (dislocation of the patella), recurrent (recurring) [adolescents/young adults].
- Patellar syndrome (synonyms: peripatellar pain syndrome); load-dependent discomfort syndrome in the patellar region, which occurs in adolescents and disappears after the completion of puberty.
- Patellofemoral pain syndrome (PFFS; synonyms: anterior knee pain, patellofemoral pain syndrome); symptomatology: pain during stress such as climbing stairs or walking downhill, partly also rest pain, esp. after prolonged knee flexion; knee extension reduces the complaints; accumulation in the 2nd and 4th decade of life; women are affected more often than men [young adults].
- Pes anserinus syndrome – Pes anserinus (goosefoot): union of the tendons of musculus sartorius, musculus semitendinosus, and musculus gracilis; via the pes anserinus, all three muscles attach to the medial aspect of the tibial body. In pes anserinus syndrome, there is overuse due to recurrent friction phenomena or direct trauma (injury), leading to both tendinitis (inflammation of the tendon) and bursitis (inflammation of the bursa) at the knee joint; symptomatology: Frequent pain as well as tenderness below the medial joint space; palpable crepitations (crackling sounds) during knee movements (occasionally present)Note: Swelling is more indicative of bursitis (bursitis).
- Plica mediopatellaris (fold in the inner joint mucosa in the knee joint) / plica syndrome.
- Popliteus tendon tendinosis – inflammatory irritation of the popliteal tendon; Symptomatology: lateral knee pain, which occurs especially at a knee flexion of about 15-30 ° and under load (esp. pronounced when running downhill and stairs); pressure painfulness over the tendon insertion in the area of the lateral femoral condyle.
- Psoriatic arthritis → joint degeneration
- Reactive arthritis – inflammation of one or more joints occurring as a result of a bacterial infection of the urinary tract, respiratory tract or intestine (Yersinia, Salmonella, Shigella and Campylobacter, for posturethritic arthritis Chlamydia, less commonly Gonococcus, possibly also Mycoplasma and Ureaplasma), but in which the causative agent is not found in the joint, instead it is an immunological reaction
- Retropatellar osteoarthritis – osteoarthritis of the femoropatellar joint between the patella and the trochlea femoris; symptomatology: pain behind the kneecap, most noticeable when walking down stairs or hills and when standing up after prolonged sitting with the knee joint bent [middle-aged and elderly patients].
- Rheumatoid arthritis → joint degeneration
- Spondylarthritis – diseases of the rheumatoid form in which there is inflammation of the small vertebral joints (spondylarthritis).
- Synovialitis (often with joint effusion) [middle age and elderly patients].
- Tendinitis patellae (synonyms: jumpers knee, patellar tendinopathy, patellar apicitis, tendinitis patellae, tendinosis patellae, enthesiopathy of the patellar tendon; jumpers knee) – chronic, painful, degenerative overuse disease of the patellar extensor apparatus [adolescents/young adults]
- Tractus iliotibialis syndrome (synonyms: runner’s knee, iliotibial band syndrome, tract syndrome); overuse-related pain in the area of the knee originating from the tractus iliotibialis; symptomatology: runner (typically endurance runner; marathon) complains of stabbing pain above the lateral knee joint space; pain may also radiate into the area of the tibial insertion
- Transient bone marrow edema syndrome (BMOE) – self-limiting disease of unclear etiology of weight-bearing joints of the lower extremity (very rare)
- Migratory KMÖS (“regional migratory osteoporosis“), special form of KMÖS; symptoms: migratory arthralgias (joint pain) of the lower extremity.
Neoplasms – tumor diseases (C00-D48).
- Neoplasms (benign/benignant u. malignant/malignant dignity), unspecified (e.g., osteosarcoma near the knee joint [adolescents/young adults])
- Metastases (daughter tumors), unspecified neoplasms.
Psyche – nervous system (F00-F99; G00-G99)
- Lesions of the peroneal nerve in the knee region – clinical picture: pain beginning at the lateral (side) knee and radiating into the lower leg and dorsum of the foot; later, paresis of the foot elevators and toe extensors as well as the pronators of the foot may occur; examination reveals localized tenderness at the level of the fibular head and a positive Hofmann-Tinel test over the peroneal nerve is elicitable
Injuries, poisoning, and other sequelae of external causes (S00-T98).
- Fracture (fracture of a bone), unspecified
- Injuries to soft tissues, unspecified
- Cartilage injuries
- Cruciate ligament injuries [adolescents/young adults]
- Meniscus injuries [see above].
Other differential diagnoses
- O- and X-leg
Differential diagnoses in monarthritis
Infectious and parasitic diseases (A00-B99).
- Chronic inflammatory gastroenteritis (gastrointestinal inflammation) with joint involvement.
- Gonorrhea (gonorrhea) – sexually transmitted infectious disease that particularly affects the synovium in joints. Prevalence: 1-2% of the population; most often women.
Musculoskeletal system and connective tissue (M00-M99).
- Activated arthroses
- Acute arthritis or acute septic arthritis – joint inflammation caused by pathogens such as bacteria (bacterial arthritis); often seen in the knee jointRisk factors for septic arthritis include advanced age (> 80 years), joint punctures, prosthesis in hip or knee joint, joint surgery, rheumatoid arthritis, diabetes mellitus, and skin infections
- Arthropathies, metabolic (gout), hemotological conditioned.
- Infectious arthritides: eg. Reiter’s disease (synonyms: Reiter’s syndrome, Reiter’s disease, urethro-oculo-synovial syndrome, arthritis dysenterica’, postenteritic reactive arthritis, sexually acquired reactive arthritis (SARA), undifferentiated oligoarthritis) – seronegative spondyloarthropathy caused by intestinal or urinary tract disease with bacteria (usually chlamydia), especially in HLA-B27 positive individuals. It can manifest as arthritis (joint inflammation), conjunctivitis (conjunctivitis), urethritis (urethritis) and partly with typical skin changes.
- Collagenoses
Neoplasms – tumor diseases (C00-D48)
- Tumors, unspecified; adolescents are most commonly affected