Effects of Volar Tilt, Wrist Extension, and Plate Position on Contact Between Flexor Pollicis Longus Tendon and Volar Plate

Wurtzel, Caroline N.W.; Burns, Geoffrey T.; Zhu, Andy F.; Özer, Kağan

doi:10.1016/j.jhsa.2017.08.008

Cited by 22 publications

(21 citation statements)

References 18 publications

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“…However, the contact pressure between the FPL and volar plate has been shown to be influenced by the position of the wrist, with an increased contact pressure with increased extension of the wrist. 19,20 These results might indicate a changing distance between all tendons and cortex depending on wrist movement. Further studies, including four-dimensional (4D)-MRI could extrapolate on our results by identifying tendon-bone distances in different positions of the wrist.…”

Section: Discussionmentioning

confidence: 81%

“…17 In previous literature, the watershed line has been used as a reference point for safe placement of volar plates. It is argued that plate placement proximal to this line decreases the contact pressure between a volar plate and the FPL 19,20 and allows for safer plate positioning. However, in this study, we found the distance between the FPL and the volar cortex decreased slightly from the watershed line and 3-mm proximal to the watershed line, and only increases 6-mm proximal to the watershed line.…”

Section: Discussionmentioning

confidence: 99%

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MRI Study on the Distance between the Distal Radius and the Flexor and Extensor Tendons: Is There Any Room for Error/Hardware?

et al. 2019

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Purpose This study aims to quantify the distances between the cortex of the distal radius and flexor and extensor tendons. Methods We analyzed 50 magnetic resonance images (MRI) of intact wrist without pathology. The distances between the volar cortex and the flexor pollicis longs (FPL), index flexor digitorum profunduns (FDPi), flexor digitorum profundus (FDP), and flexor digitorum superficialis (FDS) were measured at the level of the watershed line and 3- and 6-mm proximal to this level. The distances between the dorsal cortex and the extensor carpi radialis longus (ECRL), extensor carpi radialis brevis (ECRB), extensor pollicis longus (EPL), extensor indicis proprius (EIP), and the extensor digitorum communis (EDC) were measured at the level of Lister's tubercle and 5-mm distal to this level. Analysis was descriptive. Results At the watershed line, the FPL, FDPi, FDP, and FDS were located at an average of 3.1, 2.4, 3.6, and 5.1 mm, respectively, volar to the volar cortex. The distances of the FDP and FDS increased at 3-mm proximal to the watershed line and increased for all four tendons at 6-mm proximal to the watershed line. Dorsally, at Listers' tubercle the ECRL, ECRB, EPL, EIP, and EDC were identified at an average of 0.7, 0.5, 0.5, 2.6, and 3.2 mm, respectively, dorsal to the dorsal cortex of the distal radius. At 5-mm more distal, these tendons were located on average 1.2, 1.0, 0.7, 1.9, and 1.8 mm, respectively, dorsal to the dorsal cortex. Conclusion On the volar side, on average there is enough room for a volar plate when staying proximal to the watershed line. On the dorsal side, there is virtually no room for protruding screws as physical anatomical space is limited to a maximum of 0.7 mm from cortex to the closest tendon (the FDP), with screw increments being 2 mm. Level of Evidence This is a Level II Study.

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Section: Discussionmentioning

confidence: 81%

Section: Discussionmentioning

confidence: 99%

MRI Study on the Distance between the Distal Radius and the Flexor and Extensor Tendons: Is There Any Room for Error/Hardware?

et al. 2019

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“…Wurtzel et al. investigated plate and FPL tendon contact using cadavers and electric circuits, reporting that loss of volar tilt increased contact between the plate and FPL [23]. Fifth, although we placed the plate with the best fit in the radial–ulnar position, the plate may not be placed exactly straight because of individual differences.…”

Section: Discussionmentioning

confidence: 99%

Volar locking plates not touching the flexor pollicis longus tendon appear as prominences on radiographs: a cadaver study

et al. 2019

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Background Plate protrusion is a risk factor for flexor pollicis longus (FPL) rupture following volar locking plate (VLP) surgery. However, plate prominence on follow-up radiographs is common. We hypothesised that a VLP that does not touch the FPL tendon can appear as a plate prominence projected over the volar ridge on lateral radiographs. Materials and methods We studied six current designs of widely used plates in formalin-fixed cadavers. Each plate was placed in six cadavers. We analysed 36 different plate–cadaver combinations. The main aim of plate fixation was to position the plate in the most distal position without FPL tendon contact. Radiographs were obtained using fluoroscopy. We evaluated plate prominence from the volar ridge according to the Soong grading system. Results Soong grades 0 (plate did not extend beyond volar ridge), 1 (plate protruded beyond volar ridge) and 2 (plate directly on or located beyond the volar ridge) were observed in 23 (63.9%), 9 (25.0%) and 4 (11.1%) cadavers, respectively. VariAx, DVR and VALCP showed grade 1 prominence, whereas Acu-Loc2, HYBRIX and MODE showed grade 2 prominence. Conclusions Implant protrusion was observed in 36% of plate–cadaver combinations, even if the plate did not touch the FPL. Estimating the risk of FPL rupture using lateral radiographs alone is likely insufficient. Our findings can be applied to accurately identify the presence of implant prominence following VLP surgery.

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“…11,12 A well-recognized factor leading to tendon irritation is plate placement in relation to the most distal volar ridge of the radial metaphysis, known as the watershed line. 8,11,[13][14][15][16][17] Distal to this line, increased surface area of contact 14 and therefore glide friction 15,17 lead to tendon injury which is not always symptomatic until a tendon ruptures. Newer studies have demonstrated that plate prominence (and therefore greater impingement on tendons) can also result from not restoring the native volar tilt of the distal radius after fracture.…”

mentioning

confidence: 99%

“…Newer studies have demonstrated that plate prominence (and therefore greater impingement on tendons) can also result from not restoring the native volar tilt of the distal radius after fracture. 16 Without the native tilt, an otherwise well placed plate is more prominent in comparison to the maximal heightof the radius, and therefore comes into contact with the tendons at smaller degrees of wrist extension.…”

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confidence: 99%

Impact of Design on Force between Flexor Tendons and Distal Radius Volar Plates

et al. 2019

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Background Flexor tendon injury is a rare but serious complication of distal radius volar plating. Purpose This study aims to determine whether the design of distal radius volar plates impacts the amount of force exerted on the flexor digitorum profundus (FDP) and flexor pollicis longus (FPL) tendons when the plates are placed proximal and distal to the watershed line. Methods Three commercially available plates were applied to 10 fresh, matched-pair upper extremity specimens. Cyclical loading was applied to the tendons, and the force generated between tendon and plate was measured. Linear mixed effect models were used to evaluate differences in maximum and mean forces by plate position, plate design, and the interaction between position and design. Results Forces on the tendons differed significantly by position but not plate design. For the FPL tendon, the average maximum force with a plate in Soong's grade 2 was 4.50 (95% confidence interval [CI]: 2.8–7.3) times higher than when the plate was in a Soong's grade 0 placement, and 4.63 (95% CI: 2.82–7.61) times higher for the FDP tendon. While not statistically significant, lower observed force values with thinner plates when plates were placed distal to the watershed line suggest that that plate thickness could also be a critical plate characteristic for distally placed plates. Conclusion Despite differences in plate design, the main determinant of plate prominence and therefore flexor tendon injury potential is placement in relation to the watershed line. Clinical Relevance This study may help to guide surgeon implant selection and volar plate design.

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Effects of Volar Tilt, Wrist Extension, and Plate Position on Contact Between Flexor Pollicis Longus Tendon and Volar Plate

Cited by 22 publications

References 18 publications

MRI Study on the Distance between the Distal Radius and the Flexor and Extensor Tendons: Is There Any Room for Error/Hardware?

MRI Study on the Distance between the Distal Radius and the Flexor and Extensor Tendons: Is There Any Room for Error/Hardware?

Volar locking plates not touching the flexor pollicis longus tendon appear as prominences on radiographs: a cadaver study

Impact of Design on Force between Flexor Tendons and Distal Radius Volar Plates

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