Biomechanical Evaluation of Fourth Generation Minimally Invasive Distal First Metatarsal Osteotomy-Akin Osteotomy Technique on First Ray Articular Contact Properties.

BACKGROUND: Hallux valgus is a common deformity encountered but remains a complex clinical entity. Fourth-generation minimally invasive surgery (MIS) techniques consisting of a percutaneous distal metatarsal transverse osteotomy combined with an Akin osteotomy have been used to address mild to severe hallux valgus deformities. The benefits of an MIS approach include improved cosmesis, faster recovery, lower opiate requirement, immediate weightbearing, and favorable outcomes relative to a traditional, open procedure. An understudied area with respect to hallux valgus correction is the effect that osteotomies can have on the articular contact properties of the first ray following correction. METHODS: Sixteen paired cadaveric specimens were dissected to include the first ray and tested in a customized apparatus. Specimens were randomized to receive a distal transverse osteotomy translated either 50% or 100% of the width of the first metatarsal shaft. The osteotomy was performed with either a 0° or 20° distal angulation of the burr relative to the shaft in the axial plane. Specimens were tested in the intact state and following the distal first metatarsal osteotomy for peak pressure, contact area, contact force and center of pressure at the first metatarsophalangeal (MTP) and first tarsometatarsal (TMT) joints. An Akin osteotomy was then performed on each specimen, and peak pressure, contact area, contact force, and center of pressure were recalculated. RESULTS: There was a notable decrease in peak pressure, contact area, and contact force across the TMT joint with greater shifts of the capital fragment. However, at 100% translation of the capital fragment, distal angulation of the osteotomy by 20° appears to improve loading across the TMT joint. Addition of the Akin osteotomy at 100% translation also aids in increasing the contact force across the TMT joint. The MTP joint is less sensitive to changes in shifts and angulation of the capital fragment. The Akin osteotomy also leads to increased contact force across the MTP joint when the capital fragment is translated 100%. CONCLUSION: While the clinical significance is unknown, larger shifts of the capital fragment lead to greater load alterations at the level of the TMT joint than the MTP joint. Distal angulation of the capital fragment and the addition of an Akin osteotomy can aid in reducing the size of those changes. The Akin can lead to increased contact forces at the MTP joint with 100% translation of the capital fragment. LEVEL OF EVIDENCE: Not applicable, Biomechanical study.

The Effect of Chilled vs Room-Temperature Irrigation on Thermal Energy Dissipation During Minimally Invasive Calcaneal Osteotomy of Cadaver Specimens.

Background: Minimally invasive (MIS) calcaneal osteotomy has grown in popularity in recent years to address hindfoot deformity. A potential complication is thermal bone necrosis secondary to heat generation from the burr that may lead to osteotomy nonunion. Irrigation is commonly employed to reduce this risk. The effect of irrigation on reducing heat accumulation remains an understudied area. The purpose of this study was to evaluate the effect of cooled vs room-temperature irrigation on thermal energy dissipation during calcaneal osteotomy using a Shannon burr. Methods: Fourteen cadaveric limbs at room temperature (68 °F) were randomized to receive either cooled saline (7 limbs) or room-temperature (7 limbs) irrigation during MIS calcaneal osteotomy. Two thermocouple probes were inserted 5 mm away from the plane of the osteotomy, on the proximal and distal sides, respectively. A 3 × 30-mm Shannon burr was used to perform the osteotomy. The burr was run continuously with continuous irrigation using either room-temperature (68 °F) or chilled (37 °F) irrigation, until the osteotomy was completed. Temperature was recorded at 0, 15, 30, 45, and 60 seconds for the 2 groups and used as a measure of thermal energy accumulation. Results: Both room-temperature and chilled irrigation were effective in minimizing temperature change. On the proximal side, an overall mean increase of 2.5 °F with room-temperature irrigation and a mean decrease of 1.0 °F with chilled irrigation were observed at the 60-second interval (P = .004). On the distal side, there was a mean increase of 1.3 °F with room-temperature irrigation and a mean increase of 0.5 °F with chilled irrigation (P = .05). Conclusion: For the duration of an MIS calcaneal osteotomy, both continuous room-temperature and chilled irrigation can minimize temperature increases and potentially reduce the risk of an osteotomy nonunion. Clinical Relevance: Both room-temperature and chilled irrigation can minimize bone temperature increases during MIS calcaneal osteotomy.

Early Catastrophic Failure of a Synthetic Cartilage Implant for Hallux Rigidus.

Hallux rigidus is a common arthritic disorder of the foot. Surgical treatments are varied, from isolated cheilectomy to arthrodesis. A synthetic cartilage implant has been embraced recently as a joint-sparing alternative to arthrodesis, with good early and midterm outcomes. However, early clinical failures have been described relating to implant subsidence. This case report focuses on another mode of failure consisting of early catastrophic wear resulting in conversion to a lengthening arthrodesis at short-term follow-up.Levels of Evidence: Level V.

Management of Hallux Valgus in Metatarsus Adductus.

Metatarsus adductus is common clinical entity with an estimated prevalence of approximately 30%. Multiple radiographic methods exist to evaluate the extent of the deformity, with the Sgarlato and Engel methods most commonly used. Surgical treatment varies, consisting of proximal versus distal metatarsal osteotomies, TMT arthrodesis, and realignment of the lesser rays. Particularly in severe cases, addressing all deformities is critical to obtaining a good outcome.

State of the Art in Lesser Metatarsophalangeal Instability.

Advancements in lesser metatarsophalangeal (MTP) instability have involved the use of minimally invasive surgery techniques, synthetic augmentation of existing transfers, and use of arthroscopy for both diagnosing and addressing MTP disorder. Advances in imaging modalities, particularly MRI, have aided in diagnosing subtle instability. Clinical outcomes seem to be similar to traditional approaches as the indications and applicability continue to evolve.

Biomechanical Comparison of the Influences of 2 Proximal Metatarsal Osteotomies on First Ray Articular Contact Characteristics.

BACKGROUND: An understudied area of proximal first metatarsal osteotomies is the effect on articular contact properties following the surgeries. Potential long-term risks include altered joint mechanics and possible arthritic progression. A biomechanical comparison of articular characteristics of the proximal opening wedge and Ludloff osteotomies was performed in this study. It was hypothesized that the proximal opening wedge osteotomy (POWO) would lead to greater alterations in articular contact properties along the first ray. METHODS: Seven paired fresh-frozen below-knee cadaveric limbs with hallux valgus were selected. Specimens in each pair were tested in the intact state and then randomized to receive either a Ludloff or POWO. A 4-mm opening wedge osteotomy was used in all cases. Loading of the flexor hallucis longus was to 100 N using an instrumented tensioner. A 28-N load was added at the distal phalanx to simulate the ground reaction force. First metatarsophalangeal (MTP) and tarsometatarsal (TMT) articular properties were recorded simultaneously using 2 pressure sensors. For each state, a pressure map was generated and contact area, peak pressure, and center of pressure were calculated. Wilcoxon signed-rank test was used to assess statistical significance. RESULTS: Average peak pressure was noted to be elevated at the MTP (4.6 vs 6.9 mPa, P = .04) and TMT (3.3 mPa vs 5.1 mPa, P = .30) joints when comparing the Ludloff and the POWO, respectively. Contact area was also noted to be lower in the POWO relative to the Ludloff for the MTP (86.6 vs 69.1 mm2, P = .30) but not the TMT joints (89.1 vs 88.5 mm2, P = .97). There was a slight plantar-lateral and dorsomedial shift in pressure at the MTP and TMT articulations, respectively, of the POWO relative to the Ludloff. A trend toward decreased contact force within the TMT joint was noted following opening wedge osteotomy relative to the intact state (103.8 vs 113.9 N, P = .31), while forces were elevated at the MTP joint (104.3 vs 96.0 N, P = .63), although not statistically significant. Smaller increases in TMT and MTP joint forces were noted following the Ludloff when compared to the intact state (95.6 vs 93.3 N at TMT and 109.2 vs 103.2 N at MTP). CONCLUSION: POWO can potentially change articular contact characteristics along the TMT and MTP articulations of the first ray. This could possibly lead to altered loading patterns and possible long-term damage vs other osteotomies. CLINICAL RELEVANCE: While it is unlikely that the changes observed with the sizes of the osteotomy commonly used would lead to long-term significant clinical consequences, further study with larger group sizes would be beneficial.

Correction of moderate to severe coronal plane deformity with the STAR ankle prosthesis.

BACKGROUND: Prior studies have demonstrated a correlation between the degree of preoperative coronal plane deformity and failure following ankle replacement. We reviewed all of our patients who underwent ankle replacement utilizing the STAR prosthesis from 2000 to 2009 to evaluate the outcome of those with moderate (10 to 19 degrees) and severe (20 degrees or greater) coronal plane deformity. MATERIALS AND METHODS: Out of 130 consecutive patients, 43 patients had at least 10 degrees of preoperative coronal plane deformity. Twenty-five ankles had 10 to 19 degrees degrees of deformity and 18 ankles had 20 degrees or greater deformity. Average age was 66 years. Average length of followup was 41 (range, 12 to 98) months. RESULTS: Average talar preoperative deformity was 17.9 (range, 10 to 29) degrees, while average initial talar postoperative deformity was 3.5 (range, 0 to 12) degrees. Average final talar postoperative deformity was 4.7 (range, 0 to 14) degrees. Preoperative and final correction of deformity was statistically significant (p < 0.01), but there was no significant difference between initial and final postoperative correction. Overall, recurrence of the preoperative coronal plane deformity occurred in six of 43 patients (14%). All three patients who had deformities over 25 degrees developed recurrences. Correction of the coronal plane deformities was achieved by using intraoperative soft-tissue balancing, including deltoid ligament release in 12 patients and lateral ligament reconstruction in one patient. Deltoid ligament release was found to be necessary for all patients with greater than 18 degrees of varus plane deformity. CONCLUSION: Correction of moderate to severe coronal plane deformity with the STAR prosthesis was achievable with only soft-tissue balancing procedures with predictable results especially for deformities less than 25 degrees.

The correction of pelvic obliquity in patients with cerebral palsy and neuromuscular scoliosis: is there a benefit of anterior release prior to posterior spinal arthrodesis?

STUDY DESIGN: A retrospective study of 61 patients with cerebral palsy (CP) and neuromuscular scoliosis treated by either a combined anterior-posterior spinal arthrodesis or a posterior-only arthrodesis with the unit rod. OBJECTIVES: Compare coronal and sagittal plane radiographic outcomes in patients undergoing either a combined anterior-posterior spinal fusion (PSF) or a posterior-only fusion with the unit rod for neuromuscular scoliosis in patients with CP. SUMMARY OF BACKGROUND DATA: Although an anterior release before posterior spinal arthrodesis is commonly done for larger and stiffer neuromuscular curves, it is unclear whether or not an all-posterior construct produces similar correction in pelvic obliquity as that seen with an anterior-posterior spinal fusion. METHODS: Sixty-one consecutive children with CP and scoliosis were treated at a single institution between 1991 and 2003 with PSF using the unit rod with an anterior release (group A: 19 patients; average = 14.4 years) or without an anterior release (group B: 42 patients; average = 13.7 years). Side-bending, AP, and lateral radiographs were used to assess various sagittal and coronal plane parameters at baseline, after surgery, and at 2 years. RESULTS.: Before surgery, group A had larger major curves (91 degrees A vs. 72 degrees B; P = 0.001), less flexible major curves (21% A vs. 40% B; P = 0.01), with greater pelvic obliquity (26 degrees A vs. 19 degrees B, P = 0.02) than group B. In the subset of patients with a more severe preoperative pelvic obliquity (>20 degrees ), percent correction in pelvic obliquity was equivalent between groups A (71%) and B (74%, P = 0.91). With respect to coronal and sagittal plane radiographic outcomes, there were no significant group differences in major curve correction (58% A vs. 60% B), but group A trended toward greater % correction from preop bending films. At most recent follow-up, there were no differences with respect to loss of curve correction (7.6 A vs. 8.1 degrees B, P = 0.80). The rate of major complications was 26% for both groups, but group A patients had significantly longer operative times. CONCLUSION: We demonstrate that excellent correction in severe pelvic obliquity can be achieved in smaller, more flexible curves using an all-posterior PSF, and in larger, less flexible curves using an anterior release with PSF.

Effect of interleukin-10 overexpression on the properties of healing tendon in a murine patellar tendon model.

PURPOSE: Interleukin-10 (IL-10) is a potent anti-inflammatory cytokine shown to inhibit scar formation in fetal wound healing. The role of IL-10 in adult tendon healing and scar formation, however, remains unknown. The objective of this study is to investigate the effect of IL-10 overexpression on the properties of adult healing tendon using a well-established murine model of tendon injury and a lentiviral-mediated method of IL-10 overexpression. METHODS: A murine model of patellar tendon injury was used and animals divided into 3 groups. Mice received bilateral patellar tendon injections with a lentiviral vector containing an IL-10 transgene (n = 34) or no transgene (n = 34). Control mice (n = 34) received injections of sterile saline. All animals then were subjected to bilateral, central patellar tendon injuries 2 days after injection and were killed at 5, 10, 21, and 42 days after injury. IL-10 content was analyzed by immunohistochemistry (n = 4/group). Tendon healing was evaluated by histology (n = 4/group) and biomechanical analysis (n = 10/group). RESULTS: Overexpression of IL-10 in patellar tendon was confirmed after injection of the lentiviral vector. IL-10 immunostaining was increased at day 10 in the IL-10 group relative to that in controls. Histologically, there was no significant difference in angular deviation between groups at day 21, but a trend toward decreased angular deviation in controls relative to that in empty vector group mice was seen at day 42. Biomechanically, the IL-10 group showed significantly increased maximum stress at day 42 relative to that in controls. Percent relaxation showed a trend toward an increase at day 10 and a significant increase at day 42 in the IL-10 group relative to that in controls. CONCLUSIONS: This study demonstrates successful gene transfer of IL-10 into adult murine patellar tendon using a lentiviral vector. Although the effects of overexpression of IL-10 on adult tendon healing have not yet been fully elucidated, the current study may help to further clarify the mechanisms of tendon injury and repair.

Streamlining the evaluation of low back pain in children.

UNLABELLED: The workup of low back pain in children often results in overimaging so as not to miss organic back pain. The primary goal of this study was to identify which combination of imaging modalities provides the most sensitive and specific screening protocol for children with low back pain. Medical records from 100 consecutive patients between 2 and 18 years of age presenting with low back pain, without night pain or constitutional symptoms, were evaluated. A hyperextension test combined with a radiograph showed a negative predictive value of 0.81 and sensitivity of 0.90. The addition of a bone scan was highly effective in achieving good negative predictive value and sensitivity. Bone scans had perfect negative predictive value and sensitivity when symptom duration was less than 6 weeks. We identified a set of factors that is highly predictive for distinguishing organic back pain from mechanical back pain. Painless hyperextension combined with negative anteroposterior, lateral, and oblique lumbar radiographs and magnetic resonance images predicts mechanical back pain. For patients with nonneurologic back pain of less than 6 weeks duration, bone scan is the most useful screening test because it is accurate, accessible, inexpensive, and unlikely to require sedation. LEVEL OF EVIDENCE: Level III, diagnostic study.

The parallax effect in the evaluation of range of motion in lumbar total disc replacement.

BACKGROUND: Range of motion (ROM) has been shown to influence clinical outcomes of total disc replacement (TDR). While the parallax effect in image acquisition has been shown in the literature to influence the accuracy of a variety of measurements, this concept has not been investigated in the assessment of ROM analysis following TDR. We performed an evaluation of the influence of radiograph beam angle on "by hand" and on "gold standard" flexionextension ROM measurements in lumbar total disc replacement. The purpose of this study is to determine (1) the influence of X-ray beam angle on index level angle (ILA) measurements in lumbar TDR using the keel method, and (2) whether the out-of-plane radiographic beam effects cause a difference between true and calculated range of motion. METHODS: Eight blinded orthopaedic surgeons used the keel method to calculate ROM measurements from radiographs of a flexible Sawbones model (Pacific Research Laboratories, Inc., Vashon, Washington) implanted with a ProDisc-L device (Synthes Spine, West Chester, Pennsylvania). Radiographs were obtained at beam angles of 0°, 5°, 10°, and 15° in the sagittal plane from the device center. Calculations were compared to measurements obtained by a validated digitized software method (Quantitative Motion Analysis, QMA, Medical Metrics, Inc., Houston, Texas). Inter- and intraobserver precision and accuracy were determined. RESULTS: Compared with QMA, the radiographic keel method had an average error of 3.7°. No significant effect of variation in beam angle on interobserver precision (N = 16, P = .92) or accuracy (N = 16, P = 0.86) or intraobserver precision (N = 8, P = .09) or accuracy (N = 8, P = 0.07) of ROM measurements was identified. Repeat testing with QMA also revealed no effect of parallax and resulted in nearly identical ROM measurements. CONCLUSIONS: Accuracy and precision of the keel method to determine ROM from index level angle measurements after TDR was not affected by increases in X-ray beam angles up to 15° from the device center. CLINICAL RELEVANCE: Our study demonstrates that range of motion measurements are not influenced by parallax effect when using the keel method to determine index level angle measurements in lumbar total disc replacement.