Design-specific analysis of flexor tendon ruptures after volar plating of the distal radius Maximillian Soong, MD Gavin Bishop, MD Lahey Clinic Orthopaedic Surgery

Disclosures None of the authors have any financial relationship with any of the implant manufacturers mentioned in this presentation.

Background Flexor tendon rupture from hardware impingement is a potential complication of volar plating of the distal radius. 12%Drobetz, Int Ortho % Koval, NEHS 2007 Reported contributing factors: older-generation non-anatomic plates (pi-plate, T-plate) distal and/or anterior plate position plate lift-off from loss of reduction screwhead prominence Flexor tendon injuries from specific current-generation anatomic plate designs have been inadequately studied.

Background The “watershed line”: “… a transverse ridge located within 2 mm of the joint line on the ulnar side of the radius, and mm … on the radial side …” “Hardware placed distal to the watershed line may come in direct contact with the flexor tendons, resulting in irritation or injury.” Berglund, JAAOS 2009

Methods Retrospective review Inclusion criteria: all VLP cases from (n=228) three CAQH orthopaedic hand surgeons (n=218) Acumed Acu-Loc plate (n=208) Cases involving flexor tendon rupture were identified and analyzed by radiographs and operative notes.

Results Five cases of flexor tendon rupture among 208 cases (2.4%). 2 – FPL 1 – FDP to the index finger 1 – FDP to the long finger 1 – FDP and FDS to the index finger All five underwent hardware removal and tendon reconstruction between 4 to 45 months after initial procedure.

Results Radiographic analysis of five cases with tendon rupture: 1 – plate anterior/distal to volar rim 1 – screwheads prominent 1 – screwhead prominent, plate anterior to volar rim 2 – plate anterior to volar rim Review of the remaining cases showed that the typical position of this plate is anterior to the volar rim (thus, at the watershed line).

plate distal/anterior to volar rim screwheads prominent screwhead prominent, plate anterior to volar rim plate anterior to volar rim

Discussion Product literature for the Acumed Acu-Loc plate emphasizes the unique distal extent of the plate. “The shape of the plate allows it to sit more distal than many other volar plates … The plate surface is angled upward to accommodate and support the radial styloid.” Technique Guide, page 6 Document #CPS /2004

Discussion A recent cadaver study of several different plate designs has confirmed that the Acumed Acu-Loc plate is uniquely prominent at the watershed line. “The Acumed plate fit best [when positioned] at the watershed line, which pushes the theoretical limit set by the surrounding soft tissues.” Buzzell, JHS 2008

Discussion A recent clinical study reported five cases of FPL rupture in 201 procedures involving the Acumed Acu-Loc plate (2.5%). 2 – plate distal to volar rim 1 – screwheads prominent 2 – “not seated properly” FPL ruptures with other plates in same series: 2 of 80 (2.5%) Synthes LCP 0 of 40 (0.0%) Hand Innovations (Depuy) Casaletto, JHS(B) 2009

Discussion A clinical series using a plate with a low distal profile has shown that flexor tendon rupture can be avoided. 87 patients, Hand Innovations (DePuy) plate no ruptures Chung, JBJS 2006 DePuyAcumed

Four current volar plate designs (all LEFT radius): the Acumed plate extends beyond the watershed line radially AcumedMedartisTornierDePuy

Conclusions Flexor tendon rupture after volar plating of the distal radius is an infrequent complication. The Acumed Acu-Loc plate may be overly prominent at the watershed line, which may contribute to flexor tendon rupture, and thus future versions of this plate will address this issue.* Regardless of plate selection, care must be taken to avoid distal and/or anterior position, plate lift-off, and screwhead prominence.