Level V, expert opinion.

Background Many patients undergoing TKA have both knee and ankle pathology, and it seems likely that some compensatory changes occur at each joint in response to deformity at the other. However, it is not fully understood how the foot and ankle compensate for a given varus or valgus deformity of the knee. Questions/purposes (1) What is the compensatory hindfoot alignment in patients with end-stage osteoarthritis who undergo total knee arthroplasty (TKA)? (2) Where in the hindfoot does the compensation occur? Methods Between January 1, 2005, and December 31, 2009, one surgeon (JJC) obtained full-length radiographs on all patients undergoing primary TKA (N = 518) as part of routine practice; patients were analyzed for the current study and after meeting inclusion criteria, a total of 401 knees in 324 patients were reviewed for this analysis. Preoperative standing long-leg AP radiographs and Saltzman hindfoot views were analyzed for the following measurements: mechanical axis angle, Saltzman hindfoot alignment and angle, anatomic lateral distal tibial angle, and the ankle line convergence angle. Statistical analysis included two-tailed Pearson correlations and linear regression models. Intraobserver and interobserver intraclass coefficients for the measurements considered were evaluated and all were excellent (in excess of 0.8).Results As the mechanical axis angle becomes either more varus or valgus, the hindfoot will subsequently orient in more valgus or varus position, respectively. For every degree increase in the valgus mechanical axis angle, the hindfoot shifts into varus by À0.43°(95% confidence interval [CI], À0.76°to À0.1°; r = À0.302, p = 0.0012). For every degree increase in the varus mechanical axis angle, the hindfoot shifts into valgus by À0.49°(95% CI, À0.67°to À0.31°; r = À0.347, p \ 0.0001). In addition, the subtalar joint had a strong positive correlation (r = 0.848, r 2 = 0.72, p \ 0.0001) with the Saltzman hindfoot angle, whereas the anatomic lateral distal tibial One of the authors certifies that he (AA) has or may receive payments or benefits, during the study period an amount USD 100,000 to USD 1,000,000 from Arthrex (Naples, FL, USA), an amount less than USD 10,000 from Arthrosurface (Franklin, MA, USA), and an amount USD 100,000 to USD 1,000,000 from MTP Solutions (Logan, UT, USA). One of the authors certifies that he (JJC) has or may receive payments or benefits, during the study period an amount more than USD 1,000,001 from DePuy (Warsaw, IN, USA) and an amount less than USD 10,000 from Lippincott Williams & Wilkins (Riverwoods, IL, USA). All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research 1 editors and board members are on file with the publication and can be viewed on request. Clinical Orthopaedics and Related Research 1 neither advocates nor endorses the use of any treatment, drug, or device. Readers are encouraged to always seek additional information, including FDAapproval status, of any drug or device prior to clinical use. Each aut...

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Clamp placement in the neutral anatomical axis reduced the syndesmosis most accurately in our cadaveric model, although slight overcompression was frequently observed. Placing the clamp obliquely malreduced the unstable syndesmosis.