Technical challenges of total knee arthroplasty in skeletal dysplasia.
BACKGROUND
Total knee arthroplasty (TKA) in patients with skeletal dysplasias is particularly challenging as a result of the anatomic variances and substantial bony deformities. Little has been written regarding technical considerations that should be made when performing TKA in skeletal dysplasia.


OBJECTIVE
We describe special operative considerations that must be made when performing TKA on patients with skeletal dysplasia, including implant selection and ligamentous balancing.


METHODS
We retrospectively reviewed 12 TKAs in eight patients with varying degrees of deformity (ranging from 30° of varus to 45° of valgus) secondary to three types of skeletal dysplasias: multiple hereditary exostosis, achondroplasia, and osteogenesis imperfecta. Clinical notes, operative records, and radiographic data were reviewed. Minimum followup was 1 year (average, 4 years; range, 1-10 years).


RESULTS
We used customized implants in three of the 12 knees. Constrained tibial inserts were used in five knees. All 12 knees underwent releases (soft tissue or epicondylar osteotomy) to address gap balancing or patellar tracking. Average Knee Society scores improved from 35.9 preoperatively to 82.9 postoperatively and average function scores improved from 47.9 preoperatively to 96.7 postoperatively. Complications included two transient peroneal nerve palsies.


CONCLUSIONS
Special considerations must be made with regard to implant selection and ligamentous balancing as a result of the unusual anatomy and deformities that accompany skeletal dysplasia, but the short-term clinical results reveal consistent improvements in pain and function.


METHODS
Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
Kim
Raymond H
RH
Colorado Joint Replacement, 2535 S Downing Street, Suite 100, Denver, CO 80210, USA. rkim@co-ortho.com
Scuderi
Giles R
GR
Dennis
Douglas A
DA
Nakano
Steven W
SW
D000130:Achondroplasia / Q000150:complications; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001168:Arthritis / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects* / Q000295:instrumentation; D001696:Biomechanical Phenomena; D001848:Bone Diseases, Developmental / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology; D003120:Colorado; D005097:Exostoses, Multiple Hereditary / Q000150:complications; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D009519:New York City; D010013:Osteogenesis Imperfecta / Q000150:complications; D010147:Pain Measurement; D010149:Postoperative Pain / Q000209:etiology / Q000517:prevention & control; D018579:Patient Selection; D011474:Prosthesis Design; D011859:Radiography; D016059:Range of Motion, Articular; D020127:Recovery of Function; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome