Fluoroscopic imaging overestimates the screw tip to subchondral bone distance in a cadaveric model of slipped capital femoral epiphysis

نویسندگان

  • M.J. Heffernan
  • B. Snyder
  • H. Zhou
  • X. Li
چکیده

PURPOSE Intra-operative imaging plays a key role in screw placement for slipped capital femoral epiphysis (SCFE). Complications have been associated with inadequate screw position. The purpose of this study was to evaluate computed tomography (CT) (3D fluoroscopy) and standard fluoroscopy (C-arm) images as compared with direct anatomic measurement to determine final screw position in a cadaveric SCFE model. METHODS Osteotomy with pinning was performed at the physeal scar in ten cadaveric hips. A standardised approach-withdrawal technique was performed with C-arm images taken at 15° increments. We also obtained a CT (3D fluoroscopy) scan of each hip. The screw tip-subchondral bone (STSB) distance was measured on digital imaging software and also with a digital calliper directly when the femoral head was cut in plane to expose the STSB distance anatomically. Statistical analysis included t-tests and Fisher's exact test. RESULTS Moderate SCFE osteotomies were achieved with a mean Southwick angle (39.5° ± 7°). The 60° fluoroscopic image was found to be the most representative image (41% of the time) compared with both anteroposterior (AP) and lateral images (8% and 21%). Both fluoroscopy (2.7 ± 0.8 mm, p < 0.001) and CT (1.6 ± 0.7 mm, p = 0.03) overestimated the STSB distance compared with direct measurement (0.94 ±  0.51 mm). Two-thirds (67%) of CT measurements were within 1 mm of the cadaveric measurement, while only 20% of C-arm measurements fulfilled this criterion (p = 0.04). CONCLUSIONS Both standard fluoroscopy and CT overestimated the STSB distance when compared with direct measurement in a cadaveric model of SCFE. Surgeons should be aware of the limitations of intra-operative imaging to determine the STSB distance. We suggest that using the known pitch of a screw (2.9 mm in a 7.3-mm cannulated screw) as an intra-operative tool to help guide screw placement.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Bilateral epiphyseal migration following fixation for slipped capital femoral epiphyses in a hypothyroid child.

Progression of slipped capital femoral epiphysis following in situ screw fixation typically occurs through loosening of the screw in the metaphysis. Epiphyseal migration off the screw due to physeal growth is rare. We report epiphyseal migration off bilateral screws in a child undergoing thyroid replacement therapy. Patients with mild and moderate slipped capital femoral epiphysis and endocrine...

متن کامل

Progressive slip after removal of screw fixation in slipped capital femoral epiphysis: two case reports

UNLABELLED INTRODUCTION In slipped capital femoral epiphysis the femoral neck displaces relative to the head due to weakening of the epiphysis. Early recognition and adequate surgical fixation is essential for a good functional outcome. The fixation should be secured until the closure of the epiphysis to prevent further slippage. A slipped capital femoral epiphysis should not be confused wit...

متن کامل

Torsional Strength of Single–versus Double–screw Fixation in a Model of Unstableslipped Capital Femoral Epiphysis

INTRODUCTION: Slipped capital femoral epiphysis (SCFE) is the most common hip disorder of adolescent children [1]. It results in fracture of the growth cartilage, separating the proximal femoral epiphysis from the metaphysis, due to hormonal and mechanical factors [2]. The most widely accepted treatment for stable SCFE (defined by the ability to bear weight on the affected limb) has been a sing...

متن کامل

Intra-operative arthrography facilitates accurate screw fixation of a slipped capital femoral epiphysis.

We report the case of a 13-year-old obese child presenting with bilateral stable slipped capital femoral epiphyses, which were managed by percutaneous single screw fixation in situ under image intensifier control using arthrography.

متن کامل

Slipped capital femoral epiphysis in skeletally immature patients.

Fixation by a single screw is considered the current treatment of choice for a slipped capital femoral epiphysis. This approach promotes premature physeal closure. The use of a modified, standard, single, cannulated screw designed to maintain epiphyseal fixation without causing premature closure of the physis was reviewed in ten patients. The nine boys and one girl aged between 10.6 and 12.6 ye...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره 11  شماره 

صفحات  -

تاریخ انتشار 2017