Compression Staples Research Articles

Biomechanical Performance of 4-Leg Sustained Dynamic Compression Staples in First Tarsometatarsal Arthrodesis.

This study investigates the biomechanical efficacy of new 4-leg Sustained Dynamic Compression (SDC) NiTiNOL staples, hypothesized to offer superior stability and resilience to loading before fusion completion, compared with conventional hardware. Twenty sawbones left full foot models were divided into 4 treatment groups: (1) 4-leg Inline Staple, (2) 4-leg Inline Staple + 2-leg Staple, (3) 4-leg Inline Staple + Screw, and (4) Plate + Screw. An osteotomy was performed to simulate a Lapidus procedure, and the respective fixation methods were applied. Mechanical testing was conducted using a servo-hydraulic testing machine to evaluate constructs' load, contact force, contact area, and plantar gap. The 4-leg Inline Staple + Screw group demonstrated significantly increased joint contact force, joint contact area, and decreased plantar gap compared with the Plate + Screw group, both before and after cyclic testing. All SDC-containing constructs exhibited post-cyclic joint contact areas that were 2.36×, 3.87×, and 5.49× greater than the post-cyclic plate + screw group. Most notably, the 4-leg Inline Staple + Screw group maintained a plantar gap of less than 3 mm throughout the testing, unlike other groups. The 4-leg Inline SDC Staple, particularly when combined with a static screw, demonstrated biomechanical superiority over traditional plate and screw constructs in Lapidus procedures. These findings suggest a promising avenue for enhanced post-operative stability, which could translate into quicker patient recovery, improved fusion rates, and potentially lower non-union rates. Further clinical trials are warranted to validate these biomechanical advantages in patient outcomes. Therapeutic, Level V: Bench Testing.

The Use of Nitinol Staples as Reduction Aids in Fixation of Forearm Diaphyseal Fractures: Surgical Technique and Case Series.

Forearm diaphyseal fractures are common orthopedic injuries that typically require surgical intervention using various implants and approaches. Maintaining reduction while simultaneously achieving compression in radial and/or ulnar shaft fractures during compression plate application can be challenging, particularly with unstable segmental and/or transverse fracture patterns. Nitinol compression staples have become increasingly used as a reduction aid because of their ability to provide continuous compression between the staple legs at the fracture site, low profile, and ease of application. These staples have the potential to be an effective means of maintaining reduction and applying compression before definitive plate fixation for radial and ulnar shaft fractures. We present our surgical technique and an associated patient series detailing our institution's experience, highlighting favorable outcomes and potential considerations when using nitinol compression staples for forearm fracture management.

Clinical and Radiographic Outcomes of Nitinol Compression Staples for Midfoot and Chopart Arthrodesis

Nitinol staple use in orthopedic surgery has increased in recent years. Biomechanical studies provide useful data for use in foot/ankle; however, clinical data is limited. This study's purpose is to determine the efficacy of nitinol staples to achieve stable, bony arthrodesis in midfoot and Chopart joints, and examine their clinical outcomes and pain scores. A retrospective chart review was performed on 127 midfoot/Chopart joint arthrodeses (71 patients) using nitinol staples in isolation. The primary outcome variable was radiographic evidence of healing. Radiographs were blinded, randomized, and independently reviewed by three board certified foot and ankle surgeons. Complete/partial union was seen in 89% of all joints (113/127), increasing to 93% when including only midfoot joints (98/106). Chopart joints had significantly lower healing rates (15/21; 71%) compared to all midfoot joints (p = 0.01) and isolated tarsometatarsal joints (86/91; 95%) (p = 0.006). Neuropathy and smoking did not affect arthrodesis, but diabetes did (p = 0.004). Joints requiring bone grafting had worse rates of arthrodesis (38/49; 76%) (p = 0.002). For all joints, post-operative visual analog scale scores were significantly lower than pre-operative (p < 0.001). Pre-operative midfoot and Chopart pain scores were similar (p= 0.30). Midfoot joints had significantly lower pain scores post-operatively than pre-operatively (p < 0.001). No such significance existed in Chopart joints (p = 0.07). Isolated nitinol staples are a viable option for midfoot arthrodesis, especially tarsometatarsal joints, and offer significant pain improvement. Chopart joints may require more rigid fixation than nitinol staples, given the lower healing rate. Level of Clinical EvidenceIV

Augmented Fixation in Transverse Midshaft Humerus Fractures Using a Nitinol Staple: Surgical Technique and Case Series.

Maintaining the reduction of a transverse humeral shaft fracture can be particularly challenging while applying a compression plate for definitive fixation. Nitinol compression staples are being increasingly utilized in orthopedic surgery due to their unique ability to apply continuous compression between staple legs at body temperature. We have found them to be particularly useful in the maintenance of the reduction of transverse humeral shaft fractures before compression plate application. This simple technique allows for the removal of reduction clamps and precise plate placement. We describe our technique for using nitinol compression staples to augment fracture fixation in transverse humeral shaft fractures as well as our experience using this technique in a case series of 4 patients.

Activated nitinol compression staples are associated with favorable biomechanical properties for talonavicular arthrodesis

BackgroundNitinol compression staple use in foot and ankle arthrodesis procedures, including for the talonavicular joint, has gained acceptance. A previous study provided evidence for using nitinol compression staples in talonavicular arthrodesis (TNA) based on functional biomechanical testing comparisons to “gold standard” lag screw fixation. This study aimed to further compare the functional biomechanical properties of nitinol compression staple fixation to lag screw fixation for arthrodesis of the talonavicular joint. Body-temperature incubation and ankle inversion and eversion loading sequences were added to previously reported biomechanical testing. MethodsRobotic testing was performed on cadaveric feet (n = 10; 5 matched pairs) after TNA using either two nitinol compression staples or two fully threaded lag screws. TNA method was randomized, alternating between matched-pairs of left and right feet. After surgical stabilization, specimens were incubated at 38 °C for 24 h to simulate the initial postoperative period in a patient. After plantarflexion and dorsiflexion testing, the specimens underwent inversion and eversion testing, cycling from 20° inversion to 10° eversion for 10 cycles. Displacements were tracked using optical tracking markers. Significant (p < 0.05) differences between staple versus screw fixation cohorts were determined using paired t-Tests. ResultsAll specimens completed testing with none experiencing failure at the TNF. No statistically significant differences in functional biomechanical testing properties were noted between nitinol compression staple fixation and lag screw fixation for TNA. ConclusionThe study findings provide additional support for nitinol compression staple fixation as an option for talonavicular arthrodesis fixation. Taken together, the results of functional biomechanical testing studies have provided sufficient evidence for initiation of a prospective clinical outcomes study using nitinol compression staples for talonavicular arthrodesis fixation at our institution.

Tibial Supra-Tubercular Deflexion Osteotomy During Revision Anterior Cruciate Ligament Reconstruction

Background: A deflexion osteotomy may reduce anterior translational forces imparted upon an anterior cruciate ligament (ACL) reconstruction (ACL-R) graft, thereby reducing risk of ACL graft failure in patients with excessive congenital posterior tibial slope. Indications: A 13-year-old female competitive soccer player with 13.7° of posterior tibial slope presented with failure of a prior ACL-R. Technique Description: A vertical incision is made along the medial border of the patellar tendon and the proximal tibia is exposed. The planned osteotomy is templated under fluoroscopic guidance by placement of 2.4-mm Steinmann pins. A supra-tubercular deflexion osteotomy is made with a sagittal saw and osteotomes, with care to maintain the posterior cortical hinge. Compression staples are utilized for fixation of the osteotomy site. Revision ACL-R is then performed. Results: There were no immediate complications following surgery. Surgical management led to radiographic improvement of the patient's posterior tibial slope and clinical resolution of anterior translational knee instability. Discussion/Conclusion: The senior author's preferred technique for a tibial supra-tubercular deflexion osteotomy in association with a revision ACL-R is presented. A deflexion osteotomy is a surgical option for patients with excessive (&gt;12°) posterior tibial slope in the setting of a prior failed ACL-R. This case demonstrates the efficacy of a tibial supra-tubercular deflexion osteotomy in the revision ACL-R setting by reducing posterior tibial slope, thereby lessening anterior translational forces on the ACL graft in a patient at high risk of graft failure. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Surgical planning for staple fixation of the first tarsometatarsal joint: An anatomic study

First tarsometatarsal (TMT) arthrodesis is a common procedure utilized by foot and ankle surgeons for the management of a variety of first TMT pathology including hallux valgus and arthritis. The present study was undertaken to determine the average staple leg depth that allows for adequate purchase within the medial cuneiform and first metatarsal base at 2 different staple bridge lengths for dorsal compression across the 1st TMT joint. A cadaveric study was performed using 20 fresh-frozen below knee specimens. After TMT dissection was performed, drill holes were then created from dorsal to plantar and parallel to the first TMT joint at the distances utilized for 20 mm and 25 mm staple bridge lengths. The depths of each drill hole were measured and recorded. The mean medial cuneiform depth corresponding to a 20 mm and 25 mm staple bridge was 31.9 mm +/- 2.8 mm and 31.1 mm +/- 2.1 mm respectively (P-value = 0.38). The mean first metatarsal depth corresponding to a 20 mm and 25 mm staple bridge was 27.9 mm +/- 2.2 mm and 25.4 mm +/- 3.4 mm respectively (P-value = 0.04), showing statistical significance. Based on our anatomic data it is suggested that a 20 mm staple leg depth is consistently a safe depth when using 20×20 and 25×20 mm dorsal compression staples. However, further studies must be conducted to compare the amount of compression between the two respective staples.

Clinical and Radiographic Outcomes of Nitinol Compression Staples for Midfoot and Chopart Arthrodesis

Category: Midfoot/Forefoot; Hindfoot Introduction/Purpose: Continuous compression implant (nitinol staples) use in orthopaedic surgery has increased in recent years. There are several advantages of nitinol staples, including a lower profile when compared to traditional fixation methods. They are easy to apply and take up a smaller footprint than most plating techniques, thus decreasing surgical time and dissection. Additionally, continuous compression across the fusion site is maintained during the resorptive phase of bone healing. Biomechanical studies provide useful data supporting the use of nitinol staples in the foot and ankle; however, clinical data is limited. This study’s purpose is to determine the efficacy of nitinol staples to achieve stable, bony healing in midfoot and Chopart joint arthrodesis, and examine their clinical outcomes, complications, and pain scores. Methods: A retrospective chart review was performed on 127 midfoot/Chopart joints (71 patients) that underwent arthrodesis using nitinol staples in isolation over a five-year period (January 2017 – February 2022). The primary outcome variable was radiographic evidence of healing. Radiographs were blinded, randomized, and independently reviewed by three board certified foot and ankle surgeons. Each investigator reviewed digital radiographs independently and recorded their radiographic finding responses. Fusions were deemed healed if greater than 50% of the arthrodesis site contained bridging bone. A partially healed arthrodesis was defined as some bridging bone, but less than 50% of the overall arthrodesis site, and a nonunion was defined as no healing seen radiographically or loss of reduction. There were no cases of complete inter-surgeon radiographic disagreement in this study. Pain scores and clinical outcomes were also collected. Smokers and diabetics represented 27% (n = 19) and 13% (n=9) of the patient population, respectively. Results: Complete/partial union was seen in 89% of all joints (113/127) and 93% of midfoot joints (98/106). Chopart joints had a significantly lower healing rate (15/21; 71%) compared to midfoot joints (p = 0.013) and TMT joints in isolation (86/91; 95%) (p = 0.006). Neuropathy and smoking had no effect on healing but diabetes did (p = 0.004). Joints requiring bone grafting had a worse healing rate (38/49; 76%) (p = 0.002). For all joints, post-operative VAS scores were significantly lower than pre-operative (p &lt; 0.00001). Midfoot and Chopart pre-operative pain scores did not differ (p= 0.30), but differed post-operatively (p = 0.003). Midfoot joints had significantly lower pain scores post-operatively than pre-operatively (p &lt; 0.00001). No such significance existed in Chopart joints (p = 0.070). Conclusion: Isolated nitinol staples are a viable option for midfoot arthrodesis, especially TMT joints, and offer significant pain improvement. Staples are lower profile, decreasing hardware irritation and potential secondary surgeries, and ease of use makes insertion efficient and reproducible. They offer the benefit of continuous compression of the fusion site, and are rigid enough to maintain reduction. Chopart joints, however, may require a more rigid fixation than nitinol staples can provide, given the lower healing rate. Caution should be exercised in diabetics and joints that may require bone grafting.

Biomechanical comparison of nitinol compression staples versus fully threaded lag screws for talonavicular arthrodesis

BackgroundTalonavicular arthrodesis (TNA) is indicated for treatment of disorders that require immobilization of the hindfoot. Lag screw fixation is considered the reference standard technique for TNA. Despite consistently favorable clinical results using lag screw fixation, it is still associated with higher than desired complication and failure rates. Nitinol compression staples have been used for TNA based on potential advantages over lag screw fixation. However, functional biomechanical data comparing lag screw and nitinol compression staples for TNA are lacking. Therefore, the objective of this study was to compare nitinol compression staples to fully threaded lag screws for use in TNA with respect to their biomechanical properties during functional robotic testing. MethodsTNA was performed on cadaveric feet (n = 12; 6 matched pairs) using either two nitinol compression staples (Arthrex, Naples, FL) or two fully threaded lag screws (Arthrex, Naples, FL) in random order, alternating between paired left and right feet. After instrumentation, specimens were mounting in a robotic testing system and loaded at 89 N/sec from 30 N to 445 N for 1 min. Then, continuous compressive load of 445 N was applied while cycling from 30° plantarflexion to 15° dorsiflexion for 10 cycles. Optical tracking markers attached to the talus and navicular bone tracked displacements. Translation data were recorded along the X, Y, Z planes. Rotation data were recorded for roll, pitch, and yaw. Significant (p < 0.05) differences between fixation methods were determined using paired t-Tests for each measured variable. ResultsThere were no statistically significant differences between staples and screws for translation in X, Y, or Z planes. When comparing rotation (roll, pitch, and yaw), there were no statistically significant differences with the exception of increased roll rotation for staple fixation versus lag screw fixation during static compression testing (p = 0.009). ConclusionBased on comparison to the reference standard lag screw fixation for clinically relevant biomechanical properties measured during functional robotic testing of the hindfoot, nitinol compression staples are a viable option for talonavicular arthrodesis.

Radiographic Evaluation of Isolated Continuous Compression Staples for Akin Osteotomy Fixation

Continuous compression implants (nitinol staples) are gaining popularity secondary to their lower profile, less demanding technique, and less surgical dissection. Biomechanical support exists; however, clinical data is limited in the foot/ankle. This study's purpose is to determine the efficacy of nitinol staples to achieve stable, bony healing in Akin osteotomies and examine their clinical outcomes, complications, re-operations, and pain scores. We performed a retrospective chart review on 90 patients (93 osteotomies) who underwent an Akin osteotomy using a nitinol staple over a 2-year period. Radiographs were randomized and independently reviewed by 3 blinded foot and ankle surgeons. Osteotomies were deemed healed if greater than 50% of the osteotomy contained bridging bone, partially healed as less than 50% bridging bone, and nonunion as no healing, broken hardware, or loss of reduction. Visual analog scale pain scores were analyzed. Radiographic union was seen in 98.9% of Akin osteotomies (92/93), with no loss of reduction or broken staples (0/95). Only 3.2% (3/93) of patients returned to the operating room unplanned: 1 infection (1.1%), 1 symptomatic hardware removal (1.1%), and 1 traumatic disruption of fixation (1.1%). Postoperative pain scores were significantly lower than preoperative. Staples are lower profile and technically less demanding compared to headed screws, plates, and tension band constructs. They offer continuous compression of the osteotomy and are rigid enough to maintain reduction. Based on the findings of this paper, the use of staples provides robust and stable fixation for Akin osteotomies and has low complication and high healing rates.

Varus collapse following anterior closing wedge proximal tibial osteotomy for ACL revision reconstruction: a case series

A slope-correcting anterior closing wedge proximal tibial osteotomy is a powerful tool for correcting increased posterior tibial slope in the setting of a failed anterior cruciate ligament reconstruction. This case series documents three cases in which patients collapsed into varus following an anterior closing wedge proximal tibia osteotomy. Two patients had osteotomies fixated with a “suture-staple” construct, and all had medical comorbidities or reported noncompliance post-operatively. Therefore, meticulous care during the planning, execution, and rehabilitation phases is critical as multiple factors throughout the arc of care may contribute towards anterior closing wedge proximal tibial osteotomy varus collapse. Careful optimization of medical comorbidities and rigid fixation with either a plate and screws or compression staples should be used rather than a “suture-staple” to mitigate this risk.Level of evidence: IV.

Nitinol Shape Memory Staple Fixation of Lisfranc Fractures is Safe and Efficacious

Category: Trauma; Midfoot/Forefoot; Sports Introduction/Purpose: Surgical treatment of Lisfranc fractures has evolved from arthrodesis or transarticular screw fixation to joint preserving modalities (suture buttons and/or dorsal spanning plates), the latter commonly requiring removal due to metalwork irritation and to restore motion at the 1st-MTPJ. Shape memory staples formed from Nitinol exploit its biomechanical properties of; low Young's modulus, super elasticity and high ductility. To produce a robust implant that generates greater compressive forces at its distal end compared to traditional 316L stainless steel compression staples. Permitting the construction of a rigid fixation for Lisfranc fractures that is achieved with transarticular screws or plate fixation, but is mobile and elastic as with suture buttons. This study aims to assess the surgical outcomes of staple fixation in acute Lisfranc fractures. Methods: A prospective study to assess for union and necessity for revision surgery was completed for consecutive Lisfranc fractures treated with Nitinol shape memory staple fixation from June 2020 at a single U.K. Level 1 Major-Trauma-Centre. All operations were performed or supervised by a single fellowship trained Major Trauma Foot &amp; Ankle Surgeon through a EHL bed approach to access the base of the 2nd MT and cuneiforms. Relevant joints were debrided and reduced, held with K-wires and reduction clamps to allow for the placement of the staples. A triangular configuration for the placement of three staples (2nd MT to Middle Cuneiform, 2nd MT to Medial Cuneiform, Middle to Medial Cuneiform). Reduction of the Lisfranc complex was confirmed on intra-operative fluoroscopy. Patients were non-weight bearing for 4 weeks with appropriate VTE prophylaxis. Staples were placed so as to not penetrate the plantar cortex and inter-cuneiform instability was assessed and confirmed intra- operatively. Results: Results from 19 consecutive patients were analysed, consisting of 9 men 10 women, with a mean age of 44 years (19-76). Seven patients sustained high energy trauma. Mean time to theatre was 18 days (5-28) from date of injury. Mean total operative time was 70 minutes, (27-154) with an mean tourniquet time of 63 minutes. An mean length of follow-up was 13.5-months (range 6-20 months), with a 100% union rate on weight-bearing radiographs and no incidences of post-operative complications requiring further medical or surgical intervention. No patients reported symptomatic implant irritation which required consideration of metalwork removal. The average FADI score was 73/104 (70%) at longest follow-up. Conclusion: Nitinol shape memory staple fixation of Lisfranc fractures is safe and efficacious, removing the necessity for metalwork removal as is commonly seen with dorsal bridging plates whilst maintaining the structural rigidity of plate/trans-articular screw fixation at the same time as allowing for physiological motion at the 1st-MTPJ. Patient reported outcome measures of this technique demonstrate equitable outcomes to more conventionally used techniques. This is the largest series of shape memory alloy staple fixation of acute Lisfranc injuries the authors are aware of and demonstrates that this technique should be considered a part of a surgeons' armamentarium when treated Lisfranc injuries.

Salvage Fixation With a Single Nitinol Compression Staple for a Lateralized Fibular Tunnel in Posterolateral Corner Reconstruction of the Knee

Recognition and treatment of injuries to the posterolateral (PLC) corner of the knee have increased in recent decades. Despite advancements in surgical technique, complications can occur in up to 20% of PLC reconstructions. Lateralization of the fibular tunnel during drilling is a common intraoperative pitfall and can lead to cortical breach or fibular head fracture after graft tensioning. Compression staples have been increasingly used for fracture fixation in the hand, foot, and ankle. Because of its pseudo-elastic properties, insertion of a low-profile, compressive Nitinol staple could serve as an intraoperative salvage technique to reinforce and prevent failure through a thin lateral cortex of the fibular head. The purpose of this Technical Note is to describe a reproducible technique for the implementation of a Nitinol staple for reinforcement of a lateralized fibular tunnel in posterolateral corner reconstruction.

Mid-carpal Arthrodesis Using Staples

Limited carpal fusion offers patients with degenerative wrist conditions reliable pain relief without the complication profile of total wrist arthroplasty and preserves motion compared to total wrist fusion. The authors of this study present the technique of limited carpal fusion with nitinol memory compression staples, which offer a reliable and consistent, alternative to classic methods of intercarpal fusion. Multiple studies have demonstrated outcomes equivalent to traditional fusion alternatives.

Radiographic Evaluation of Isolated Continuous Compression Staples for Akin Osteotomy Fixation

Category:Bunion; OtherIntroduction/Purpose:The use of continuous compression implants (nitinol staples) in orthopaedic surgery has increased secondary to advances in metal alloy engineering. Biomechanical studies provide useful data supporting the theoretical use of nitinol staples in the foot and ankle. However, clinical data is limited. The purpose of this study was to determine the overall effectiveness, both clinically and radiographically, of continuous compression implants (nitinol staples) to achieve bony healing in the medially based, closing-wedge osteotomy of the proximal phalanx of the great toe (Akin osteotomy).Methods:A retrospective chart review was performed on 104 patients (107 feet) who underwent an Akin osteotomy using nitinol staples between January 1st, 2018 and February 20th, 2020. The primary outcome variable was radiographic evidence of healing on x-ray. X-rays were independently reviewed by three board-certified foot and ankle surgeons. All investigators were blinded towards the x-rays, and x-rays were randomized in terms of timing from surgery. Each investigator reviewed digital radiographs independently and recorded their radiographic finding responses. Osteotomies were deemed healed if greater than 50% of the osteotomy contained bridging bone. A partially healed osteotomy was defined as some bridging bone, but less than 50% of the overall osteotomy site, and a nonunion was defined as no healing seen radiographically, broken hardware, or loss of reduction.Results:Radiographic union (partial or full) was seen in 95% of Akin osteotomies (96/101) based on our parameters, with no loss of initial reduction. Only 2.8% (3/107) of the patient population had unplanned return to the operating room for reasons associated with the Akin osteotomy: one infection (0.9%), one irritable hardware removal (0.9%), and one traumatic disruption of fixation (0.9%). None of the eligible staples (0/106) were found to be fractured upon radiographic analysis. Smokers and diabetics represented 4.8 and 8.7 percent of the patient population, respectively.Conclusion:Since its inception in 1925, the Akin osteotomy has been described using several types of fixation methods. The results of this retrospective study show that continuous compression implants (nitinol staples) are a viable option for Akin osteotomy fixation, with low rates of complications (2.8%, 3/107) and high healing rates (95%, 96/101). Staples are lower profile, eliminating hardware irritation and potential secondary surgeries, are technically less demanding, and time of application is decreased when compared to other fixation methods. They offer the benefit of continuous compression of the fusion site, as well, and are rigid enough to maintain reduction.

Radiographic Evaluation of Isolated Continuous Compression Staples for Midfoot and Chopart Arthrodesis

Category:Midfoot/Forefoot; HindfootIntroduction/Purpose:The use of continuous compression implants (nitinol staples) in orthopaedic surgery has increased secondary to advances in metal alloy engineering. Biomechanical studies provide useful data supporting the theoretical use of nitinol staples in the foot and ankle; however, clinical data is limited. There are several advantages of nitinol staples, including a lower profile when compared to traditional fixation methods. They are easy to apply and take up a smaller footprint than most plating techniques, thus decreasing surgical time and dissection. Additionally, continuous compression across the fusion site is maintained, as opposed to lag screw fixation. The purpose of this study was to determine the overall effectiveness, clinically and radiographically, of continuous compression implants (nitinol staples) to achieve stable arthrodesis in the midfoot and Chopart joints.Methods:A retrospective chart review was performed on 18 patients (37 joints) who underwent arthrodesis of the midfoot or Chopart joints utilizing isolated continuous compression implants between January 2017-December 2019. The primary outcome variable was radiographic evidence of arthrodesis on x-ray. X-rays were independently reviewed by three board-certified foot and ankle surgeons. All investigators were blinded towards the x-rays, and x-rays were randomized in terms of timing from surgery. Each investigator reviewed digital radiographs independently and recorded their radiographic finding responses. Joints were deemed fused if greater than 50% of the joint contained bridging bone radiographically. A partial fusion was defined as some bridging bone, but less than 50% of the joint involved, and nonunion was defined as no arthrodesis seen radiographically, broken hardware, or loss of reduction. Smokers and diabetics represented 22% and 11% of the patient population, respectively.Results:Radiographic union was seen in 88.8% of TMT joints (16/18) and 83.3% of midfoot joints overall (20/24). Nonunion rates were 11.2% (2/18) and 16.6% (4/24) respectively. Diabetes was associated for 50% (3/6) of nonunions. Mean time-to-fusion for TMT joints was 60 days. In Chopart joint fusions, nonunion rate was 46% (6/13), 2/6 (33%) were smokers. Overall, diabetes and smoking was associated with 40% (4/10) of all nonunion cases. TMT joint fusions had a significantly lower proportion of nonunion rates than hindfoot fusions (p=0.043). Radiographic Interobserver reliability was moderately strong between reviewers. Clinically, Chopart joint fusion patients had a significantly longer time course to weight bearing (p = 0.028). 8% (4/50) had broken hardware, all in nonunions, 75% (3/4) occurring in Chopart joints.Conclusion:Isolated nitinol staples are a viable option for midfoot arthrodesis, especially TMT joints, and offer multiple advantages when compared to traditional fixation methods. Staples are lower profile, eliminating hardware irritation and potential secondary surgeries, are technically less demanding, and time of application is decreased when compared to other methods. They offer the benefit of continuous compression of the fusion site, as well, and are rigid enough to maintain reduction. However, Chopart joints may require a more rigid fixation than CCI staples can provide, given the higher nonunion rate, and caution should be exercised in diabetics and smokers.

Effect of Bone Quality and Leg Depth on the Biomechanical Performance of a Nitinol Staple

The use of Nitinol compression staples has increased in foot and ankle procedures due to their ease of delivery and ability to offer sustained, dynamic compression. Prior biomechanical studies have predominantly examined mechanical performance in healthy bone models without investigating the effect of unicortical versus bicortical fixation. The purpose of this study was to examine the effect of bone quality and staple leg depth on the biomechanical performance of Nitinol staples in a bicortical bone model. Two-legged Nitinol staples were implanted in bicortical sawbone of 2 densities. Two different leg depths were tested to simulate unicortical versus bicortical fixation. Interfacial compressive forces, interfacial compression area, torsional strength, and shear strength were measured for each group. The effect of leg depth was minimal compared to the effect of sawbone density on the mechanical performance of Nitinol staples. Interfacial compressive force and interfacial compression areas were greater in the low density bone model, while torsional strength and shear strength were greater in the normal density bone model. Nitinol staple's mechanical performance is highly dependent upon bone quality and less dependent on whether staple legs terminate in cancellous versus cortical bone. Low density bone allows for a higher compressive interfacial area to be imparted by the staple. Staples in normal density bone are able to resist torsion and shear deformation more readily than staples in low density bone. Bone density may have a greater effect on the Nitinol staple's stability and compressive capability in vivo as compared to unicortical versus bicortical leg fixation.

Retrospective Comparison of Capitolunate Arthrodesis Using Headless Compression Screws Versus Nitinol Memory Staples for SLAC and SNAC Wrist: Radiographic, Functional, and Patient-Reported Outcomes.

Nitinol memory compression staples have been proposed as an effective alternative to compression screws for capitolunate arthrodesis (CLA) for scaphoid nonunion advanced collapse (SNAC) and scapholunate advanced collapse (SLAC) wrist. The purpose of this study was to compare the clinical outcomes of CLA for SNAC or SLAC wrist treatment using either compression screws or nitinol staples. In all, 47 patients with CLA for SLAC or SNAC wrist with screws or nitinol staples were retrospectively identified. Primary outcome was fusion on radiographs and/or computed tomography. Secondary outcomes were hardware-related complications (HWCs) and other complications, range of motion, grip strength, and patient-reported outcome measures (PROMs), including Visual Analogue Pain scale; Disabilities of the Arm, Shoulder, and Hand score; and patient-rated wrist evaluation. Of the 47 eligible patients, 40 (85%) were included: 31 patients in the staple group and 9 patients in the screw group. The average age was 49 (17-80) years. There was an 89% union rate for the screw group and a 97% union rate for the staple group. Two patients had screw backout: one who went onto union after screw removal and the other who went onto nonunion after hardware removal. There were 2 (6.5%) HWCs in the staple group. One patient had staple loosening requiring revision and the other dorsal impingement requiring staple removal after radiographic union. In all subsequent cases, the staples were countersunk with no impingement. No significant differences existed between any additional outcomes. We found no differences between nitinol staples and screws for CLA regarding HWCs or PROMs. Nitinol staples may offer additional benefits as a safe and effective alternative to compression screws for wrist fusions.

Outcomes of Nitinol Compression Staples in Tarsometatarsal Fusion.

Background:Tarsometatarsal (TMT) arthrodesis is commonly performed in the management of midfoot arthritis, trauma, or deformity. The purpose of this study was to collect aggregate data (demographic, surgical, and perioperative outcomes) on patients who previously had a TMT fusion with BME compression staples.Methods:Sixty-six patients underwent TMT fusion with BME compression staples. Outcomes included demographics, surgical information, the Veterans Rand VR-12 Health Survey, Foot and Ankle Ability Measure (FAAM), visual analog scale (VAS), Revised-Foot Function Index (FFI-R), Ankle Osteoarthritis Scale (AOS), patient satisfaction survey scores, radiographic fusion rate, level of pain reduction, and complications. Sixty-six patients (68 feet) were analyzed (59 females) with an average age of 64 years (range, 18-83). The mean latest follow-up was 35.9 (range, 6-56.6 months).Results:The average surgical time was 38.1±14.3 minutes (range, 11-75). All outcomes improved significantly (P < .001) from preoperative to latest follow-up except for the VR-12 Mental and Physical score. The average time to fusion determined by radiographs was 8.4 weeks (range, 6.1-46.1 weeks). Wound complications were not seen. Indications for subsequent surgeries (26.5%, 18/68 feet) in this current study included pain (n = 14), broken staples, and nonunion (n = 3).Conclusions:The fusion rate in this study, 89.7%, was similar to values reported in the literature. The patient satisfaction score of 81.9 at latest follow-up is consistent with patient satisfaction for other methods of fusion.Level of Evidence:Level IV, retrospective case series.

The Use of Nitinol Compression Staple Fixation and Bone Graft for Scaphoid Waist Fractures and Nonunion: A Surgical Technique

In the management of scaphoid fractures, nonunion is an important complication that can lead to carpal instability and early-onset arthritis. Various techniques have been described to treat scaphoid nonunions, yet a clear consensus on the superiority of one method is not yet established. The use of compression staple fixation has been described in the literature and may be a viable alternative to other fixation techniques. Volar Nitinol staple fixation avoids damage to the trapezium during retrograde fixation with a screw. It also avoids damage to the proximal dorsal cartilage, which occurs during anterograde screw fixation. Because of its shape and position on the volar aspect of the scaphoid, staple fixation provides compression, prevents graft extrusion, and avoids taking up space in the medullary canal of the scaphoid. Moreover, it may be technically easier than screw fixation. Despite these advantages, this technique has not been widely adopted. We describe the technique for utilizing Nitinol compression staples and bone grafting in the treatment of scaphoid nonunion.