Working Diagnosis:
Patellofemoral pain syndrome in setting of Nail-Patella syndrome

Treatment:
The patient was prescribed a home exercise plan in addition to Physical Therapy referral. Treatment focused on hip and knee strengthening as well as biomechanical balancing.

Outcome:
The patient was seen in follow up 5 weeks after treatment initiation with improvement in pain, improvement in strength, and improved tolerance to patellofemoral loading movements.

Author's Comments:
Patellofemoral Pain Syndrome (PFPS) is a condition of anterior knee pain due to dysfunction of biomechanical forces while loading the patellofemoral joint. PFPS is one of the most common forms of knee pain, more common in females, and has a prevalence cited between 15%-45%. Nail-Patella Syndrome (NPS) is an autosomal dominant genetic disorder of chromosome 9, affecting the gene LMX1B. The disorder affects males and females equally, and the frequency of occurrence is 1/50,000. NPS results in poorly developed nails and patellae, but can affect other areas of the body as well. Around 90% of cases involve the patella, with 20% having aplastic patellae, and commonly associated with symptomatic knee instability.

Editor's Comments:
Anterior knee is a common complaint seen among Sports Medicine Physicians. Patellofemoral Pain Syndrome, Nail Patella Syndrome (NPS), also termed hereditary osteo-onychodysplasia disease or Fong disease, is a rare autosomal dominant genetic mutation resulting in a variety of abnormalities. Associated findings include hypoplastic or absent patellae, naibed and distal digit abnormalities such as swan neck deformity, elbow dysplasia (often of the radial head), pterygia, posterior iliac horns, as well as hearing and visual pathology. Glomerular basement membrane collagen expression by LMX1B can lead to renal disease in patients with NPS, necessitating caution with nephrotoxic medications such as NSAIDs. Literature review showed prenatal ultrasound findings in the developing fetus; however, this is a unique example of diagnostic ultrasound images in NPS.

References:
Alexandra Price, MD; Jessica Cervantes, BS; Scott Lindsey, MD; Divya Aickara, MS; Shasa Hu, MD. Nail-Patella Syndrome: Clinical Clues for Making the Diagnosis. Cutis, 2018, 101,126-129.
Gaitonde DY, Ericksen A, Robbins RC. Patellofemoral Pain Syndrome. Am Fam Physician. 2019 Jan 15;99(2):88-94. PMID: 30633480.
Lippacher S, Mueller-Rossberg E, Reichel H, Nelitz M. Correction of malformative patellar instability in patients with nail-patella syndrome: a case report and review of the literature. Orthop Traumatol Surg Res 2013; 99:749.
Sweeney E, Fryer A, Mountford R, et al. Nail patella syndrome: a review of the phenotype aided by developmental biology Journal of Medical Genetics 2003;40:153-162.
Tigchelaar S, Rooy Jd, Hannink G, et al. Radiological characteristics of the knee joint in nail patella syndrome. Bone Joint J 2016; 98-B:483.

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