Tibial Tuberosity Transposition Fixation with a Locking Plate during Medial Patellar Luxation Surgery: An Ex Vivo Mechanical Study

Objectives The purpose of this study was to compare the load at failure, stiffness and mode of failure between three types of tibial tuberosity transposition fixation techniques: (a) pin and figure-8 tension band wire (Pin-TBW), (b) locking plate with pin and a tension band wire (Plate-Pin-TBW) and (c) locking plate with a pin (Plate-Pin). Methods Six pairs of raccoon dog cadaveric tibiae were tested in Phase I Pin-TBW versus Plate-Pin-TBW and seven pairs in Phase II Plate-Pin-TBW versus Plate-Pin. One limb of each pair was randomly assigned to one of two groups for each phase. A tensile force was applied to the patellar ligament until construct failure. Results Pin-TBW (342N ± 54.7N) failed at a lower load than Plate-Pin-TBW (469N ± 77.3N), p = 0.00748, with all Pin-TBW failing by fracture and the majority of Plate-Pin-TBW failing by rupture of patellar ligament. Pin-TBW group Phase I, normalized with Plate-Pin-TBW Phase I, failed at a lower load than Plate-Pin group Phase II, normalized with Plate-Pin-TBW Phase II, p = 0.00467. There was no significant difference in mean load at failure, stiffness or mode at failure between the groups in the Phase II study. Clinical Significance Although ex vivo mechanical testing does not replicate the postoperative live dog or cat, these results demonstrate lower construct strength of the Pin-TBW construct compared with the Plate-Pin construct in the raccoon dog cadaver model.

Surgical management of ulnar styloid fractures: comparison of fixation with anchor suture and tension band wire

Background: Limited reference is available regarding surgical management in symptomatic ulnar styloid fractures with small bony avulsion. The study goal is to report the surgical outcomes using anchor suture fixation with comparison to traditional tension band wire fixation.Methods: We retrospectively reviewed the medical records in patients who underwent surgical repair for unilateral ulnar styloid fractures with distal radioulnar instability between 2004 and 2017. A total of 31 patients were enrolled including two kinds of fixation methods. Anchor suture fixation plus distal radioulnar joint pinning was performed in ten patients with tiny avulsion bony fragments (group A); tension band wire fixation was performed in 21 patients with big styloid fracture fragments (group B). Patient characteristics and 2-year treatment outcomes were compared between two groups based on Mayo Modified Wrist Score (MMWS), Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH), visual analog scale (VAS) and surgical complication. Descriptive statistics were used for calculation of key variables; a p-value of < 0.05 was considered statistically significant. Results: Based on Gaulke classification, there were five subtypes in group A and three subtypes in group B. Incidence of concomitant distal radius fractures was significantly higher in group B; other patient characteristics including age, sex, injury side, and time to surgery showed no significant difference. Outcome assessment regarding MMWS, QuickDASH and VAS was comparable between two groups. Bone-related complications including nonunion, DRUJ subluxation and styloid resorption were analyzed; the difference was not significant. Incidence of implant-related complications including migration and secondary removal surgery was significantly higher in group B (p = 0.021). Conclusion: Surgical fixation in symptomatic ulnar styloid fractures yields comparable treatment outcomes in both fracture patterns. Implant-related complication with secondary removal surgery is more common in tension band wire group. Anchor suture fixation is a feasible option for tiny styloid avulsion fragments with limited surgical complication.

Surgical management of ulnar styloid fractures: comparison of fixation with anchor suture and tension band wire

Background Limited reference is available regarding surgical management in symptomatic ulnar styloid fractures with small bony avulsion. The study goal is to report the surgical outcomes using anchor suture fixation with comparison to traditional tension band wire fixation. Methods We retrospectively reviewed the medical records in patients who underwent surgical repair for unilateral ulnar styloid fractures with distal radioulnar instability between 2004 and 2017. A total of 31 patients were enrolled including two kinds of fixation methods. Anchor suture fixation plus distal radioulnar joint pinning was performed in ten patients with tiny avulsion bony fragments (group A); tension band wire fixation was performed in 21 patients with big styloid fracture fragments (group B). Patient characteristics and 2-year treatment outcomes were compared between two groups based on Mayo Modified Wrist Score (MMWS), Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH), visual analog scale (VAS) and surgical complication. Descriptive statistics were used for calculation of key variables; a p-value of < 0.05 was considered statistically significant. Results Based on Gaulke classification, there were five subtypes in group A and three subtypes in group B. Incidence of concomitant distal radius fractures was significantly higher in group B; other patient characteristics including age, sex, injury side, and time to surgery showed no significant difference. Outcome assessment regarding MMWS, QuickDASH and VAS was comparable between two groups. Bone-related complications including nonunion, DRUJ subluxation and styloid resorption were analyzed; the difference was not significant. Incidence of implant-related complications including migration and secondary removal surgery was significantly higher in group B (p = 0.021). Conclusion Surgical fixation in symptomatic ulnar styloid fractures yields comparable treatment outcomes in both fracture patterns. Implant-related complication with secondary removal surgery is more common in tension band wire group. Anchor suture fixation is a feasible option for tiny styloid avulsion fragments with limited surgical complication.

Surgical management of ulnar styloid fractures: comparison of fixation with anchor suture and tension band wire

Background Limited reference is available regarding surgical management in symptomatic ulnar styloid fractures with small bony avulsion. The study goal is to report the surgical outcomes using anchor suture fixation with comparison to traditional tension band wire fixation.Methods We retrospectively reviewed the medical records in patients who underwent surgical repair for unilateral ulnar styloid fractures with distal radioulnar instability between 2004 and 2017. A total of 31 patients were enrolled including two kinds of fixation methods. Anchor suture fixation plus distal radioulnar joint pinning was performed in ten patients with tiny avulsion bony fragments (group A); tension band wire fixation was performed in 21 patients with big styloid fracture fragments (group B). Patient characteristics and 2-year treatment outcomes were compared between two groups based on Mayo Modified Wrist Score (MMWS), Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH), visual analog scale (VAS) and surgical complication. Descriptive statistics were used for calculation of key variables; a p-value of < 0.05 was considered statistically significant.Results Based on Gaulke classification, there were five subtypes in group A and three subtypes in group B. Incidence of concomitant distal radius fractures was significantly higher in group B; other patient characteristics including age, sex, injury side, and time to surgery showed no significant difference. Outcome assessment regarding MMWS, QuickDASH and VAS was comparable between two groups. Bone-related complications including nonunion, DRUJ subluxation and styloid resorption were analyzed; the difference was not significant. Incidence of implant-related complications including migration and secondary removal surgery was significantly higher in group B (p = 0.021).Conclusion Surgical fixation in symptomatic ulnar styloid fractures yields comparable treatment outcomes in both fracture patterns. Implant-related complication with secondary removal surgery is more common in tension band wire group. Anchor suture fixation is a feasible option for tiny styloid avulsion fragments with limited surgical complication.

A Cadaveric Evaluation of Pin and Tension Band Configuration Strength for Tibial Tuberosity Osteotomy Fixation

Objective The purpose of this study was to compare the load at failure and mode of failure of four constructs used to stabilize a tibial tuberosity osteotomy, including two vertically aligned pins (V), two horizontally aligned pins (H), two vertically aligned pins with a tension band wire (V-TB) and two horizontally aligned pins with a tension band wire (H-TB). Study Design Eighteen pairs of cadaveric tibiae were randomized to receive a TB or no TB. One limb was randomized to be in the H or V group. The contralateral limb was then assigned to the opposite configuration. One pair of limbs was used as a control. A tensile force was applied to the patellar ligament until construct failure. Results There was no significant difference between the mean load at failure of the H (595 N) and V (556 N) groups or between H-TB (1032 N) and V-TB groups (1034 N) (p = 0.487 and p = 0.238, respectively). The TB constructs were significantly stronger than the pin only constructs (p < 0.001). The mode of failure was similar for the pin only constructs, regardless of pin orientation. The TB constructs and control tibias failed at similar loads, most commonly by patellar ligament rupture. Conclusion The use of vertically aligned pins versus horizontally aligned pins does not affect construct strength. These results support the placement of pins in a vertically or horizontally aligned fashion. When performing a tibial tuberosity osteotomy, the addition of a TB adds significant strength to the construct.

Evaluating Wire Configurations for Tension Band Constructs using a Canine Greater Trochanteric Osteotomy Model

Objective: To investigate the stability of four tension band wiring configurations alone without the contributions of K-wire stabilization. Study design: ex vivo experimentalSample population: Sixty-four tension band wiring constructsMethods: Four tension band configurations were applied to a metal trochanteric osteotomy model based on a canine femur: figure-of-eight with one twist (OT), figure-of-eight with two twists (TT), dual interlocking single loop (DISL), and double loop (DL). Configurations were mechanically tested under both monotonic loading (n = 8 per configuration) and incremental cyclic loading (n = 8 per configuration). Initial tension after tying, residual tension remaining after each cycle, and failure load at 2 mm of displacement (considered equivalent to clinical failure) were recorded. Results: The initial tension and the load to 2 mm of displacement was lower for OT wires compared to TT wires. The DL was the strongest and most stable configuration, generating greater initial tension, maintaining a greater percentage of residual tension under incremental cyclic loads, and resisting higher load before failure at 2 mm. Failure load was highly correlated with initial tension. Conclusion: This model enabled evaluation of tension band wire configuration independent of the fixation pin portion of the construct. Wire configurations that can be tightened to a greater tension during tying, like the DL, are better able to resist the tensile loads experienced by the construct. Clinical impact: In clinical situations where high tensile loads are expected, a tighter, more secure tension band wire configuration may be warranted.