Attenuated patella alta is an extremely rare condition affecting mobility and leg strength. It is characterized by an unusually small knee cap (

patella The patella (: patellae or patellas), also known as the kneecap, is a flat, rounded triangular bone which articulates with the femur (thigh bone) and covers and protects the anterior articular surface of the knee joint. The patella is found in m ...

) that develops out of and above the

joint A joint or articulation (or articular surface) is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole.Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw- ...

. Typically, as the knee cap sits in the joint, it is stimulated to growth by abrasion from the opposing bones. When not situated properly in the joint, the knee cap does not experience such stimulation and remains small and undeveloped. Note that the cartilage under and around the kneecap is eight times smoother than ice, so "abrasion" may not be the best term. A similar condition, patella alta, can occur as the result of a sports injury, though the large majority of the time it is a congenital/developmental condition that is unrelated to trauma. A kneecap in an "alta" position sits above the "trochlear groove" and therefore is less stable. The "patellar tendon" that connects the kneecap to the tibia (shinbone) is elongated (longer than normal). This cannot happen by way of trauma, unless there has been a rupture of the tendon and a less-than-optimal surgical repair. There have been only three documented case of the disorder noted from birth. In 1988, three-year-old Eric Rogstad of

Minneapolis, Minnesota Minneapolis is a city in Hennepin County, Minnesota, United States, and its county seat. With a population of 429,954 as of the 2020 United States census, 2020 census, it is the state's List of cities in Minnesota, most populous city. Locat ...

was discovered to have the condition in both knees after several attempts by his parents and family

physician A physician, medical practitioner (British English), medical doctor, or simply doctor is a health professional who practices medicine, which is concerned with promoting, maintaining or restoring health through the Medical education, study, Med ...

to discover the cause of his difficulties with

walking Walking (also known as ambulation) is one of the main gaits of terrestrial locomotion among legged animals. Walking is typically slower than running and other gaits. Walking is defined as an " inverted pendulum" gait in which the body vaults o ...

and

running Running is a method of terrestrial locomotion by which humans and other animals move quickly on foot. Running is a gait with an aerial phase in which all feet are above the ground (though there are exceptions). This is in contrast to walkin ...

. After

surgery Surgery is a medical specialty that uses manual and instrumental techniques to diagnose or treat pathological conditions (e.g., trauma, disease, injury, malignancy), to alter bodily functions (e.g., malabsorption created by bariatric surgery s ...

and

physical therapy Physical therapy (PT), also known as physiotherapy, is a healthcare profession, as well as the care provided by physical therapists who promote, maintain, or restore health through patient education, physical intervention, disease preventio ...

, Eric gained the ability to walk and run without significant difficulty. Surprisingly, in 2016, two cases were discovered. 42 year old Anne Stone of Birmingham, England, and 27 year old Michael Brennan of Phoenix, Arizona, were independently diagnosed with bilateral attenuated patella alta. Insall Ratio: This ratio is calculated with the knee flexed to 30 degrees. It is the ratio of the length of the patella to the length of the patellar tendon. Typically, this ratio is 1:1 but 20% variation represents patella alta or patella infera. Actually, the Insall-Salvati ratio can be measured at any degree of flexion, which is one reason for its popularity.Grelsamer, RP: Patellar Malalignment - Current Concepts. J Bone Joint Surg. 82A:1639-1650, 2000

References

Musculoskeletal disorders Knee injuries and disorders {{musculoskeletal-disease-stub

See also

References