Santaram Vallurupalli

Screw Fixation Compared with Suture-Button Fixation of Isolated Lisfranc Ligament Injuries

BACKGROUND A cannulated screw is currently used to reduce and stabilize diastasis at the Lisfranc joint. The screw requires removal and may break in situ. A suture button does not have these disadvantages, but it is not known if it can provide stability similar to that provided by a cannulated screw or an intact Lisfranc ligament. The objective of the present study was to compare the stability provided by a suture button with that provided by a screw when used to stabilize the diastasis associated with Lisfranc ligament injury. METHODS Fourteen fresh-frozen, paired cadaveric feet were dissected to expose the dorsal region. A registration marker triad consisting of three screws was fixed to the first cuneiform and the second metatarsal. A digitizer was utilized to record the three-dimensional positions of the registration markers and their displacement in test conditions before and after cutting of the Lisfranc ligament and after stabilization of the joint with either a suture button or a cannulated screw. The first and second cuneiforms and their metatarsals were removed, and the ligament attachment sites were digitized. Displacement at the Lisfranc ligament and the three-dimensional positions of the bones were determined. RESULTS Loading with the Lisfranc ligament cut resulted in displacement that was significantly different from that after screw fixation (p = 0.0001), with a difference between means of 1.2 mm. Likewise, loading with the Lisfranc ligament cut resulted in a displacement that was significantly different from that after suture-button fixation (p = 0.0008), with a difference between means of 1.00 mm. No significant difference in displacement was found between specimens fixed with the suture button and those fixed with the screw. CONCLUSIONS Suture-button fixation can provide stability similar to that provided by screw fixation in cadaver specimens after isolated transection of the Lisfranc ligament.

Allograft Compared with Autograft Infection Rates in Primary Anterior Cruciate Ligament Reconstruction

BACKGROUND Injuries to the anterior cruciate ligament are the most common surgically treated knee ligament injury. There is no consensus regarding the optimal graft choice between allograft and autograft tissue. Postoperative septic arthritis is an uncommon complication after anterior cruciate ligament reconstruction. The purpose of this study was to compare infection rates between procedures with use of allograft and autograft tissue in primary anterior cruciate ligament reconstruction. METHODS A combined prospective and retrospective multicenter cohort study was performed over a three-year period. Graft selection was determined by the individual surgeon. Inclusion and exclusion criteria were equivalent for the two groups (allograft and autograft tissue). Data collected included demographic characteristics, clinical information, and graft details. Patients were followed for a minimum of 5.5 months postoperatively. Our primary outcome was intra-articular infection following anterior cruciate ligament reconstruction. RESULTS Of the 1298 patients who had anterior cruciate ligament reconstruction during the study period, 861 met the criteria for inclusion and formed the final study group. Two hundred and twenty-one patients (25.6%) received an autograft, and 640 (74.3%) received an allograft. There were no cases of septic arthritis in either group. The 95% confidence interval was 0% to 0.57% for the allograft group and 0% to 1.66% for the autograft group. The rate of superficial infections in the entire study group was 2.32%. We did not identify a significant difference in the rate of superficial infections between autograft and allograft reconstruction in our study group. CONCLUSIONS While the theoretical risk of disease transmission inherent with allograft tissue cannot be eliminated, we found no increased clinical risk of infection with the use of allograft tissue compared with autologous tissue for primary anterior cruciate ligament reconstruction.

Comparison of Augmentation Methods for Internal Fixation of Osteoporotic Ankle Fractures

Background: Internal fixation of osteoporotic ankle fractures is associated with failure of fixation. This study compared different augmentation methods biomechanically. Materials and Methods: In nine paired fresh-frozen cadaver legs, an identical supination-external rotation type II ankle fracture was created. Fractures were stabilized using an eight-hole locking plate. In four pairs, two screws were inserted across the syndesmosis for purchase in the tibial metaphysis. One leg from each pair was randomly selected for injection of calcium sulphate-calcium phosphate graft into the screw holes. Each leg was mounted to an MTS machine in a custom loading frame. Axial cyclic loading to body weight was performed to measure displacement at the fracture site, followed by rotational loading to failure simulating a supination external rotation injury. Data were analyzed using a two-way paired t -test and ANOVA. Results: The specimens used had a mean bone mineral density of 0.49 ± 0.15 (SD) g/cm2, and a mean age of 83 ± 12 years. In the biomechanical tests, there were no significant differences between augmented and non-augmented locking plates without the tibia-pro-fibula screws in axial stiffness (p = 0.10), external rotation angle at failure (p = 0.42), failure torque (p = 0.57), energy absorbed before failure (p = 0.47), and motion at the fracture site with cyclic axial loading (p = 0.15). There were no significant differences between augmented and non-augmented locking plates with the tibia-pro-fibula screws in the external rotation angle at failure (p = 0.83), failure torque (p = 0.58), and failure energy (p = 0.4). However, the overall strength of the fixation tended to increase with tibia-pro-fibula screws and augmentation. Conclusion: Internal fixation of an osteoporotic lateral malleolar fracture using a locking plate and screws provided a construct comparable in strength to that augmented with calcium sulfate-calcium phosphate graft and/or tibia-pro-fibula screws. Clinical Relevance: Strategies to augment internal fixation of osteoporotic ankle fractures may minimize risk for failure of fixation and may enable early weight bearing mobilization and return to function in elderly patients.

The use of calcium sulfate and calcium phosphate composite graft to augment screw purchase in osteoporotic ankles.

Background: Screws placed in the distal fibula may not have satisfactory purchase during internal fixation of an osteoporotic ankle fracture. Tibia-pro-fibula screws that extend from the fibula into the distal tibial metaphysis provide additional purchase. The purpose of this study was to investigate if purchase of these screws can be enhanced further by injecting calcium sulfate and calcium phosphate composite graft into the drill holes prior to insertion of the screws. Materials and Methods: Bone density was quantified using a DEXA scan in paired cadaver legs. One leg from each pair was randomly selected for injection of composite graft into the screw holes before insertion of the screws. Two screws were inserted through the fibula into the distal tibial metaphysis in each leg, at the level of the syndesmosis under fluoroscopy in a standardized fashion in an MTS machine. Results: After testing 4 pairs of cadaver legs, a statistically significant difference was noted in displacement (p = 0.018 distal, p = 0.0093 proximal), failure load, (p = 0.0185 distal, p = 0.0238 proximal), and failure energy (p = 0.0071 distal, p = 0.0115 proximal) between augmented and non-augmented screws, with the augmented screws being considerably stronger. Conclusion: Screws augmented with composite graft provide significantly greater purchase in an osteoporotic fibular fracture model. Clinical relevance: Composite graft augmented screws inserted into the distal tibia from the fibula may enhance the stability of internal fixation of an osteoporotic ankle fracture. This may enable earlier weightbearing and return to function which is important in elderly patients.

A minimally disruptive model and three-dimensional evaluation of Lisfranc joint diastasis.

BACKGROUND There is no model that can reproduce the diastasis at the Lisfranc joint after isolated transection of the Lisfranc ligament. Prior models required extensive sectioning of ligaments in the midfoot and represent injuries that cause extensive tarsometatarsal fracture-dislocations. They do not represent a subset of injuries that cause subtle or limited disruption at the Lisfranc joint. The purpose of this study was to create a model with the minimum amount of ligamentous disruption and loading necessary to consistently observe diastasis at the Lisfranc joint. METHODS Fourteen fresh-frozen paired cadaver feet were dissected to expose the dorsum. Three screws were inserted into each first cuneiform and second metatarsal to create a pair of registration triads. A digitizer was utilized to record the three-dimensional positions of the screws and their displacement under loaded and unloaded conditions before and after the Lisfranc ligament was cut (intact and cut conditions). The first and second cuneiforms and their metatarsals were removed, and the attachment sites of the dorsal and the Lisfranc ligament were digitized. The three-dimensional positions of the bones and ligament displacement were determined. The significance of differences between conditions was tested with analysis of variance, and linear regression analysis was used to test the correlation between dorsal and plantar displacements. RESULTS There was a significant difference, of 1.3 mm, in the mean displacement between the cut loaded and intact loaded conditions (p < 0.0001). A modest correlation (r(2) = 0.60) was found between dorsal displacement and displacement at the site of the Lisfranc ligament, possibly attributable to rotations between the first cuneiform and second metatarsal. CONCLUSIONS Isolated sectioning of the Lisfranc ligament is sufficient to consistently create diastasis at the Lisfranc joint. Dorsal displacements between the first cuneiform and second metatarsal are a modest predictor of plantar displacements.

Minimally invasive total hip arthroplasty with the anterior approach

Background: Total hip athroplasty with the anterior surgical approach is advised because the dissection is entirely within intermuscular planes. In this report we describe a minimally invasive technique of anterior total hip arthroplasty, with the early outcomes. Materials and Methods: The technique of minimally invasive total hip arthroplasty with anterior approach (Smith-Petersen) is described. We reviewed data on 100 consecutive patients who underwent anterior total hip arthroplasty with uncemented components. Mean patient age was 61 years (range 33-91). Mean patience BMI 29.8 (range 18.1-51.8). Results: Minumum follow up duration is 10 months. The mean duration of surgery was 53 min (range 34-87) with mean blood loss 185 cc (range 65-630), and the mean incision length was 10.4 cm. Clinical and radiographic outcomes were similar to historical outcomes of standard total hip arthroplasty. Conclusions: With proper surgeon training, minimally invasive total hip replacement with the anterior surgical interval is safe and efficacious.

Ethnic radiographic foot differences.

Background: The prevalence of foot and ankle conditions varies among different ethnic groups. It is not known if this difference is due to any distinctive skeletal morphological characteristics of the foot. The purpose of this study was to determine if ethnic differences exist in the morphometric measurements on radiographs of the weightbearing foot. Materials and Methods: A morphometric study of weightbearing radiographs of feet was performed prospectively. Radiographic parameters were measured on digital monitors using digital tools. These were the hallux valgus angle (HVA), intermetatarsal angle (IMA), talonavicular angle (TNA), talonavicular coverage angle (TNCovA), metatarsal span (MS) on anteroposterior (AP) radiographs and talo-first metatarsal angle (T-1stMTA), calcaneal pitch (CP), and lateral talocalcaneal angle (LTCA) on lateral radiographs. Results: A total of 237 feet in 126 patients (45 African Americans, 59 Caucasians, and 22 Hispanics) were studied. Statistically significant differences were found in the CP, LTCA, and MS. African Americans have significantly lower CP than Caucasians (p < 0.0001). African Americans have significantly lower CP than Hispanics (p < 0.0016). Caucasians have significantly higher TCA than African Americans (p < 0.0004). Males have a larger MS than females (p < 0.0001). Conclusion: There are differences in the radiographic morphology of feet among different ethnic groups. A larger prospective community-based study of morphological differences is needed for better understanding of the genetic and environmental factors influencing the prevalence of foot and ankle conditions. Clinical Relevance: The clinical relevance between having a lower CP angle and a higher incidence of flat feet in African Americans warrants further investigation. It is not known if there is a relationship between posterior tibialis insufficiency and low CP.

Minimally Invasive Method of Harvesting the Flexor Digitorum Longus Tendon: A Cadaver Study

Background: The flexor digitorum longus (FDL) tendon is harvested for use in the reconstruction of dysfunctional adjacent tendons such as the posterior tibial and the Achilles tendons. The approach to harvest the FDL tendon in the midfoot region is through an incision along the medial border of the foot. This approach involves dissection quite deep in the foot across neurovascular structures in the vicinity placing them at risk. The purpose of this cadaver study was to test the feasibility and safety of a minimally invasive technique, and also to define the relevant topographical surface and deeper surgical anatomy. Methods: In 83 cadaver feet, the FDL tendon was harvested proximally in the hindfoot after it was cut through a small plantar incision in the midfoot. All the tissues superficial to the FDL tendon were then reflected to check for damage to the adjacent neurovascular structures. Measurements were obtained to define the location of the point of division of the FDL tendon in relation to the plantar surface of the foot and the adjacent neurovascular structures. Results: In all of the 83 feet it was possible to harvest the FDL using this technique. In 11 feet (13.25%), a connecting band to the flexor hallucis longus tendon (FHL) required division. No damage was apparent to the adjacent neurovascular structures. The FDL division was located topographically on the plantar surface of the foot, approximately midway between the back of the heel and the base of the second toe and at this midpoint, about two-thirds of the width medially from the lateral border of the foot. Conclusions: The FDL tendon can be harvested in the hindfoot after its division through a small plantar incision in the midfoot. Surface anatomy guides placement of the plantar incision over the FDL division. Clinical relevance: The plantar approach when compared to the medial approach for harvesting the FDL tendon in the midfoot may be associated with a smaller incision, minimal dissection, lesser risk to adjacent neurovascular structures and lesser morbidity.

Tensioning of anterior cruciate ligament hamstring grafts: comparing equal tension versus equal stress.

PURPOSE A biomechanical study was undertaken to determine whether equal-stress or equal-tension tensioning of anterior cruciate ligament 4-stranded semitendinosus and gracilis grafts provides a stronger graft construct when testing to ultimate failure. METHODS Eighteen fresh-frozen cadaveric semitendinosus and gracilis tendons were each positioned over a cylinder rod/cryo-clamp connected to an MTS machine (MTS Systems, Eden Prairie, MN) by another cryo-clamp. In the equal-tension group the 4 strands were equally tensioned by weights. In the equal-stress group a tensioning device applied equal stress based on the cross-sectional areas of the tendons. The tendons were preconditioned with 10 cycles and then tested to failure. Graft creep during the preconditioning cycle was determined by MTS measurement of the change in clamp distance. RESULTS The maximum loads of 4-stranded semitendinosus and gracilis grafts tensioned by equal stress were found to be similar to those of the grafts tensioned by equal tension (2,803 +/- 431 N and 2,772 +/- 461 N, respectively). The loads at first failure were 2,640 +/- 468 N and 2,452 +/- 461 N, respectively (P = .17). The preconditioning cycles showed that the equal-stress group resisted graft creep significantly better (P = .0003). CONCLUSIONS The strength of the 4-stranded hamstring graft when equally tensioned or equally stressed was equivalent when tested to failure. After 10 preconditioning cycles, equal stress resisted graft creep significantly better. Equal-stress tensioning offers an alternative tensioning method for 4-stranded hamstring grafts. CLINICAL RELEVANCE Equal-stress tensioning offers an alternative tensioning method for 4-stranded hamstring grafts.

Segmental stiffness achieved by three types of fixation for unstable lumbar spondylolytic motion segments.

Objective The objective of this study was to compare the relative stability in lumbar spondylolysis (SP) of a rigid anterior plate (with a novel compression slot) versus traditional posterior pedicle screw (PS) fixation. Summary of Background Data Arthrodesis has been a mainstay of treatment for symptomatic isthmic spondylolisthesis in adults. Posterior PS fixation has become a commonly used adjunct. Some have advocated anterior lumbar interbody fixation (ALIF) plate as an alternative. The relative stability afforded by ALIF in SP has not been well characterized, nor has the contribution afforded by a compression screw slot in an ALIF plate. Methods Calf spine segments were characterized in the normal state, after sectioning the pars (SP model), then after reconstruction with an interbody spacer and either PS/rods, or an ALIF plate, or both. Results ALIF plate conferred stability on the spondylolytic segment only comparable to that of the normal functional spinal unit (FSU). Posterior fixation was more stable than anterior fixation in all testing modes. Addition of an ALIF plate conferred a significant additional stability in those that already had posterior fixation. The utilization of an anterior compression screw conferred additional stability in extension testing only. Conclusions ALIF plate reconstruction in the setting of SP may not confer enough segmental stability to predictably encourage fusion beyond that of the uninstrumented intact FSU. The utilization of an integral compression screw in an ALIF plate may not confer clinically significant additional construct stability in SP.