A combination of medical tests are used to diagnosis kniest dysplasia. These tests can include:

- Computer Tomography Scan(CT scan) - This test uses multiple images taken at different angles to produce a cross-sectional image of the body.

- Magnetic Resonance Imaging (MRI) - This technique proves detailed images of the body by using magnetic fields and radio waves.

- EOS Imaging - EOS imaging provides information on how musculoskeletal system interacts with the joints. The 3D image is scanned while the patient is standing and allows the physician to view the natural, weight-bearing posture.

- X-rays - X-ray images will allow the physician to have a closer look on whether or not the bones are growing abnormally.

The images taken will help to identify any bone anomalies. Two key features to look for in a patient with kniest dysplasia is the presence of dumb-bell shaped femur bones and coronal clefts in the vertebrae. Other features to look for include:

- Platyspondyly (flat vertebral bodies)

- Kyphoscoliosis (abnormal rounding of the back and lateral curvature of the spine)

- Abnormal growth of epiphyses, metaphyses, and diaphysis

- Short tubular bones

- Narrowed joint spaces

Genetic Testing - A genetic sample may be taken in order to closely look at the patient's DNA. Finding an error in the COL2A1 gene will help identify the condition as a type II chondroldysplasia.

Exact diagnosis remains widely built on precise history taking, with the characteristic clinical and radiographic skeletal features. Genetic diagnosis is based on DNA sequencing. Because plasma COMP levels are significantly reduced in patients with COMP mutations, such as pseudoachondroplasia, measuring plasma COMP levels has become a reliable means of diagnosing this and pathopysiologically similar disorders.

Diagnosis should be based on the clinical and radiographic findings and a genetic analysis can be assessed.

X-Ray

Bubbly lytic lesion / Ground glass

Imaging tests. Computerized tomography or magnetic resonance imaging scans may be used to determine how extensively your bones are affected.

Bone scan. This test uses radioactive tracers, which are injected into your bloodstream. The damaged parts of your bones take up more of the tracers, which show up more brightly on the scan.

Biopsy. This test uses a hollow needle to remove a small piece of the affected bone for laboratory analysis.

Ischiopatellar dysplasia is usually identified through radiographic evidence since its characteristic changes are most notable in radiographic tests that indicate delayed boneage or absent ossification. A full skeletal survey should be performed on any patient that has an absent or hypoplastic patellae since they could potentially have ischiopatellar dysplasia. Magnetic resonance imaging (MRI) is especially helpful in the diagnosis of ischiopatellar syndrome and is recommended when an individual affected by ischiopatellar dysplasia has a traumatic injury to the knee.

Accurate assessment of plain radiographic findings remains an important contributor to diagnosis of pseudoachondroplasia. It is noteworthy that vertebral radiographic abnormalities tend to resolve over time. Epiphyseal abnormalities tend to run a progressive course. Patients usually suffer early-onset arthritis of hips and knees. Many unique skeletal radiographic abnormalities of patients with pseudoachondroplasia have been reported in the literature.

- Together with rhizomelic limb shortening, the presence of epiphyseal-metaphyseal changes of the long bones is a distinctive radiologic feature of pseudoachondroplasia.

- Hypoplastic capital femoral epiphyses, broad short femoral necks, coxa vara, horizontality of acetabular roof and delayed eruption of secondary ossification center of os pubis and greater trochanter.

- Dysplastic/hypoplastic epiphyses especially of shoulders and around the knees.

- Metaphyseal broadening, irregularity and metaphyseal line of ossification. These abnormalities that are typically encountered in proximal humerus and around the knees are collectively known as “rachitic-like changes”.

- Radiographic lesions of the appendicular skeleton are typically bilateral and symmetric.

- Oval shaped vertebrae with anterior beak originating and platyspondyly demonstrated on lateral radiographs of the spine.

- Normal widening of the interpedicular distances caudally demonstrated on anteroposterior radiographs of the dorsolumbar region. This is an important differentiating feature between pseudoachondroplasia and achondroplasia.

- Odontoid hypoplasia may occur resulting in cervical instability.

The disorder is progressive, with the ultimate severity of symptoms often depending on age of onset. In severe cases amputation has been performed when conservative measures such as physical therapy and regional anesthetics have been ineffective.

Osteogenesis imperfecta is a rare condition in which bones break easily. There are multiple genetic mutations in different genes for collagen that may result in this condition. It can be treated with some drugs to promote bone growth, by surgically implanting metal rods in long bones to strengthen them, and through physical therapy and medical devices to improve mobility.

Because kniest dysplasia can affect various body systems, treatments can vary between non-surgical and surgical treatment. Patients will be monitored over time, and treatments will be provided based on the complications that arise.

"Osteosclerosis", an elevation in bone density, is normally detected on an X-ray as an area of whiteness, and is where the bone density has significantly increased. Localized osteosclerosis can be caused by injuries that compress the bone, by osteoarthritis, and osteoma.

Some tests which detect cancer could be called "screening for epithelial dysplasia". The principle behind these tests is that physicians expect dysplasia to occur at the same rate in a typical individual as it would in many other people. Because of this, researchers design screening recommendations which assume that if a physician can find no dysplasia at certain time, then doing testing before waiting until new dysplasia could potentially develop would be a waste of medical resources for the patient and the healthcare provider because the chances of detecting anything is extremely low.

Some examples of this in practice are that if a patient whose endoscopy did not detect dysplasia on biopsy during screening for Barrett's esophagus, then research shows that there is little chance of any test detecting dysplasia for that patient within three years.

Individuals at average-risk for colorectal cancer should have another screening after ten years if they get a normal result and after five years if they have only one or two adenomatous polyps removed.

The term thanatophoric is Greek for "death bearing". Children with this condition are usually stillborn or die shortly after birth from respiratory failure, however a small number of individuals have survived into childhood and a very few beyond. Survivors have difficulty breathing on their own and require respiratory support such as high flow oxygen through a canula or ventilator support via tracheostomy. There may also be evidence of spinal stenosis and seizures.

The oldest known living TD survivor is a 29-year-old female. One male lived to be 26 years old. Another male lived to age 20. TD survivor, Chrisopher Álvarez, 18, is Colombian living in New York. Two children with TD aged 10 and 12, a male and a female, are known in Germany. There is also a 6-year-old male living with TD and two 1-year old males.

Treatment in fibrous dysplasia is mainly palliative, and is focused on managing fractures and preventing deformity. There are no medications capable of altering the disease course. Intravenous bisphosphonates may be helpful for treatment of bone pain, but there is no clear evidence that they strengthen bone lesions or prevent fractures. Surgical techniques that are effective in other disorders, such as bone grafting, curettage, and plates and screws, are frequently ineffective in fibrous dysplasia and should be avoided. Intramedullary rods are generally preferred for management of fractures and deformity in the lower extremities. Progressive scoliosis can generally be managed with standard instrumentation and fusion techniques. Surgical management in the craniofacial skeleton is complicated by frequent post-operative FD regrowth, and should focus on correction of functional deformities. Prophylactic optic nerve decompression increases the risk of vision loss and is contraindicated.

Managing endocrinopathies is a critical component of management in FD. All patients with fibrous dysplasia should be evaluated and treated for endocrine diseases associated with McCune–Albright syndrome. In particular untreated growth hormone excess may worsen craniofacial fibrous dysplasia and increase the risk of blindness. Untreated hypophosphatemia increases bone pain and risk of fractures.

Osteofibrous dysplasia is treated with marginal resection with or without bone grafting, depending on the size of the lesion and the extent of bony involvement. However, due to the high rate of recurrence in skeletally immature individuals, this procedure is usually postponed until skeletal maturity.

Early journal reports of boomerang dysplasia suggested X-linked recessive inheritance, based on observation and family history. It was later discovered, however, that the disorder is actually caused by a genetic mutation fitting an autosomal dominant genetic profile.

Autosomal dominant inheritance indicates that the defective gene responsible for a disorder is located on an autosome, and only one copy of the gene is sufficient to cause the disorder, when inherited from a parent who has the disorder.

Boomerang dysplasia, although an autosomal dominant disorder, is "not" inherited because those afflicted do not live beyond infancy. They cannot pass the gene to the next generation.

Spondyloepimetaphyseal dysplasia is a genetic condition affecting the bones.

Types include:

- Spondyloepimetaphyseal dysplasia, Strudwick type

- Spondyloepiphyseal dysplasia congenita

- Spondyloepimetaphyseal dysplasia, Pakistani type

MRI will help with the diagnosis of structural abnormality of the brain. Genetic testing may also be pursued.

Till date about 18 cases of Spondylocostal dysostosis have been reported in literature.

Symptomatic individuals should be seen by an orthopedist to assess the possibility of treatment (physiotherapy for muscular strengthening, cautious use of analgesic medications such as nonsteroidal anti-inflammatory drugs). Although there is no cure, surgery is sometimes used to relieve symptoms. Surgery may be necessary to treat malformation of the hip (osteotomy of the pelvis or the collum femoris) and, in some cases, malformation (e.g., genu varum or genu valgum). In some cases, total hip replacement may be necessary. However, surgery is not always necessary or appropriate.

Sports involving joint overload are to be avoided, while swimming or cycling are strongly suggested. Cycling has to be avoided in people having ligamentous laxity.

Weight control is suggested.

The use of crutches, other deambulatory aids or wheelchair is useful to prevent hip pain. Pain in the hand while writing can be avoided using a pen with wide grip.

Spondyloepiphyseal dysplasia congenita (abbreviated to SED more often than SDC) is a rare disorder of bone growth that results in dwarfism, characteristic skeletal abnormalities, and occasionally problems with vision and hearing. The name of the condition indicates that it affects the bones of the spine (spondylo-) and the ends of bones (epiphyses), and that it is present from birth (congenital). The signs and symptoms of spondyloepiphyseal dysplasia congenita are similar to, but milder than, the related skeletal disorders achondrogenesis type 2 and hypochondrogenesis. Spondyloepiphyseal dysplasia congenita is a subtype of collagenopathy, types II and XI.

Most countries have standard newborn exams that include a hip joint exam screening for early detection of hip dysplasia.

Sometimes during an exam a "click" or more precisely "clunk" in the hip may be detected (although not all clicks indicate hip dysplasia). When a hip click (also known as "clicky hips" in the UK) is detected, the child's hips are tracked with additional screenings to determine if developmental dysplasia of the hip is caused.

Two maneuvers commonly employed for diagnosis in neonatal exams are the Ortolani maneuver and the Barlow maneuver.

In order to do the Ortolani maneuver it is recommended that the examiner put the newborn baby in a position in which the contralateral hip is held still while the thigh of the hip being tested is abducted and gently pulled anteriorly. If a "clunk" is heard (the sound of the femoral head moving over the acetabulum), the joint is normal, but absence of the "clunk" sound indicates that the acetabulum is not fully developed. The next method that can be used is called the Barlow maneuver. It is done by adducting the hip while pushing the thigh posteriorly. If the hip goes out of the socket it means it is dislocated, and the newborn has a congenital hip dislocation. The baby is laid on its back for examination by separation of its legs. If a clicking sound can be heard, it indicates that the baby may have a dislocated hip. It is highly recommended that these maneuvers be done when the baby is not fussing, because the baby may inhibit hip movement.

The condition can be confirmed by ultrasound and X-ray. Ultrasound imaging yields better results defining the anatomy until the cartilage is ossified. When the infant is around 3 months old a clear roentgenographic image can be achieved. Unfortunately the time the joint gives a good x-ray image is also the point at which nonsurgical treatment methods cease to give good results. In x-ray imaging dislocation may be indicated if the Shenton's line (an arc drawn from the medial aspect of the femoral neck through the superior margin of the obturator foramen) does not result in a smooth arc. However, in infants this line can be unreliable as it depends on the rotation of the hip when the image is taken ()

Asymmetrical gluteal folds and an apparent limb-length inequality can further indicate unilateral hip dysplasia. Most vexingly, many newborn hips show a certain ligamentous laxity, on the other hand severely malformed joints can appear stable. That is one reason why follow-up exams and developmental monitoring are important. Frequency and methods of routine screenings in children is still in debate however physical examination of newborns followed by appropriate use of hip ultrasound is widely accepted.

The Harris hip score (developed by William H. Harris MD, an orthopedist from Massachusetts) is one way to evaluate hip function following surgery. Other scoring methods are based on patients' evaluation like e.g. the Oxford hip score, HOOS and WOMAC score. Children's Hospital Oakland Hip Evaluation Scale (CHOHES) is a modification of the Harris hip score that is currently being evaluated.

Hip dysplasia can develop in older age. Adolescents and adults with hip dysplasia may present with hip pain and in some cases hip labral tears. X-rays are used to confirm a diagnosis of hip dysplasia. CT scans and MRI scans are occasionally used too.

Infants with type 1 thanatophoric dysplasia also have curved thigh bones, flattened bones of the spine (platyspondyly) and shortened thoracic ribs. Note: Prenatal ultra-sound images of the ribs sometimes appear asymmetrical when in fact they are not. In certain cases, this has caused a misdiagnosis of Osteogenisis Imperfecta (OI) type II.

An unusual head shape called kleeblattschädel ("cloverleaf skull") can be seen with type 2 thanatophoric dysplasia.

Spondylocostal dysostosis is a rare, heritable axial skeleton growth disorder. It is characterized by widespread and sometimes severe malformations of the vertebral column and ribs, shortened thorax, and moderate to severe scoliosis and kyphosis. Individuals with Jarcho-Levin typically appear to have a short trunk and neck, with arms appearing relatively long in comparison, and a slightly protuberant abdomen. Severely affected individuals may have life-threatening pulmonary complications due to deformities of the thorax. The syndrome was first described by Saul Jarcho and Paul M. Levin at Johns Hopkins University in 1938.

Ischiopatellar dysplasia is sometimes referred to as Scott-Taor syndrome after the researchers who first described ischiopatellar dysplasia as they recognized it in a family as an autosomal dominant disorder in 1979. This finding was important as they were the first to note that it was a benign disorder that is separate from the more severe nail-patella syndrome. Other common names for ischiopatellar syndrome are small patella syndrome (SPS), since the patellae are often small or absent in patients who have this syndrome, and coxo-podo-patellaire syndrome.

Polyostotic fibrous dysplasia is a form of fibrous dysplasia affecting more than one bone.

McCune-Albright syndrome includes polyostotic fibrous dysplasia as part of its presentation.

One treatment that has been used is bisphosphonates.