Gregory P. Guyton

Theoretical Limitations of the AOFAS Scoring Systems: An Analysis Using Monte Carlo Modeling:

The AOFAS foot scores are four related outcome instruments based on the use of quantitative interval data and have seen increasing use in the literature. The mathematical construction of the scales is particularly notable for a very small number of intervals available to answer each component item and for quantitatively unequal intervals for some items. Monte Carlo computer modeling techniques were used to simulate the responses to each item for a variety of idealized patient populations with several different means, standard deviations, and levels of interaction between items. The continuous data describing each patients responses were categorized into the finite number of available intervals in the AOFAS Hindfoot score. The resultant distributions of net scores often demonstrated bizarre, skewed behavior that bore little resemblance to the original distributions of continuous data. The effects were magnified as the ends of the scale were approached and when strong correlations between the items measuring pain and function were present. The distributions did not become distorted when the original continuous data were not rounded off into intervals but were simply weighted by their relative contribution to the AOFAS score and summed. The AOFAS scores, therefore, have inherently limited precision which is entirely due to the small number of response intervals available to answer each component item of the scale. Minor changes in a patients response to a series of correlated questions can potentially make a drastic difference in their total score. Because the population distributions may be badly skewed, the use of parametric statistics with the AOFAS scores should be regarded with genuine suspicion, and appropriate refinements of the scales should be sought.

An analysis of iatrogenic complications from the total contact cast.

Background: Many physicians continue to fear iatrogenic complications of the total contact cast, and use of this modality has remained restricted to a segment of the orthopaedic and podiatric communities. I examined the actual rate of complications and the factors associated with them in a large consecutive series of total contact casts drawn from the practice of a single surgeon to determine whether this modality is safe for multiple conditions in the neuropathic foot and ankle. Method: A consecutive series of 398 total contact casts spanning a 28-month period from the practice of a single physician were analyzed. All casts were placed by the same team of orthotists. This study comprised 70 patients with severe peripheral neuropathy; an average of 5.69 sequential casts per patient were placed. Three-hundred and sixty-seven casts were placed in diabetic patients, and 31 in patients with idiopathic peripheral neuropathy. By protocol, the initial cast was changed at an interval of no more than 1 week. On occasion, subsequent casts were left on longer, but on average casts were left in place for 7.69 days. Logistic regression analysis was used to analyze the contribution of patient factors to the chance of ulceration. Results: Complications occurred in 22 casts, including six new pretibial ulcers, six new midfoot ulcers, four forefoot or toe ulcers, five hindfoot ulcers, and one malleolar ulcer. In no case was a preexisting ulcer made worse. This corresponds to an overall complication rate of 5.52% per cast. Overall, 30% of patients suffered one complication during the course of their treatment. With one exception, all new ulcers healed with simple modalities within 3 weeks, often with continued total contact casting. A single cast led to a proximal interphalangeal ulceration that exposed the joint and eventually required toe amputation. The rate of permanent sequelae from cast-related injuries was therefore 0.25%. In no case were the resultant odds ratios statistically different from 1.0, but several trends were observed. Charcot arthropathy represented the highest risk (odds ratio 1.46), while the presence of neuropathic ulceration was surprisingly benign (odds ratio 0.69). The presence of diabetes as opposed to other causes of neuropathy was associated with increased risk (odds ratio 1.34). The use of a cast after deformity-correcting surgery in a neuropathic patient was remarkably safe (odds ratio 0.44), as were casts in which the patient was instructed to remain nonweightbearing (odds ratio 0.27). Patient age was not a factor (odds ratio 1.03). The length of time the cast was left on was not statistically important (odds ratio 0.99), although strict protocols for cast changing likely altered this data. Conclusion: A frequently changed total contact cast is a safe modality for the offloading and immobilization of the neuropathic foot, albeit with an expected constant rate of minor, reversible complications. Patients should be informed of these complications and risks before cast application.

Lateral column calcaneal lengthening, flexor digitorum longus transfer, and opening wedge medial cuneiform osteotomy for flexible flatfoot : A biomechanical study

Background: Lengthening of the lateral column is commonly used for reconstruction of the adult and pediatric flatfoot, but can result in supination of the foot and symptomatic lateral column overload. The addition of a medial cuneiform osteotomy has been used to redistribute forces to the medial column. The combined use of a lateral column lengthening and medial cuneiform osteotomy in a reproducible cadaver flatfoot model was evaluated. Methods: Twelve cadaver specimens were physiologically loaded and each was evaluated radiographically and pedobarographically in the following conditions: 1) intact, 2) severe flatfoot, 3) lateral column lengthening with simulated flexor digitorum longus transfer, and 4) lateral column lengthening and flexor digitorum longus (FDL) transfer with added medial cuneiform osteotomy. The lateral column lengthening was performed with a 10-mm foam bone wedge through the anterior process of the calcaneus, and the medial cuneiform osteotomy was performed with a dorsally placed 6-mm wedge. Results: Lateral column lengthening with simulated FDL transfer on a severe flatfoot model resulted in a significant change as compared with the flatfoot deformity in three measurements: in lateral talus-first metatarsal angle (−17 to − 7 degrees; p < 0.001), talonavicular angle (46 to 24 degrees; p < 0.001), and medial cuneiform height (16 to 20 mm; p < 0.001). Lateral forefoot pressure increased from 24.6 to 33.9 kPa (p < 0.001) after these corrections as compared with the flatfoot. Adding a medial cuneiform osteotomy decreased the lateral talar-first metatarsal angle from −7 to −4 degrees, decreased the talonavicular coverage angle from 24 to 20 degrees, and increased the medial cuneiform height from 20 to 25 mm. After added medial cuneiform osteotomy, lateral pressure was significantly different from that of the flatfoot (p = 0.01) and was not significantly different from that of the intact foot (p = 0.14). Medial forefoot pressure was overcorrected as compared with the intact foot with added medial cuneiform osteotomy. Conclusions: Lateral column lengthening increased lateral forefoot pressures in a severe flatfoot model. An added medial cuneiform osteotomy provided increased deformity correction and decreased pressure under the lateral forefoot.

Effect of Extracorporeal Shock Wave Therapy on Cultured Tenocytes

BACKGROUND Little has been reported about the biologic effect of shock waves on human normal or pathologic tendon tissue. We hypothesized that inflammatory cytokine and MMP production would be down-regulated by shock wave stimulation. MATERIALS AND METHODS Diseased Achilles tendon tissue and healthy flexor hallucis longus tissue were used. Shock wave treatment was applied to cultured cells at 0.17 mJ/mm(2)energy 250, 500, 1000, and 2000 times. RESULTS A dose-dependent decrease in cell viability was noted in cells receiving 1000 and 2000 shocks (86.0 +/- 5.6%, p = 0.01 and 72.4 +/- 8.9%, p = 0.001) as compared with the normal control. Cell count in the 500-shock group increased by 23.4% as compared with the control (p = 0.05). The concentration of MMP 1, 2, and 13 was higher in diseased tenocytes as compared with normal cells (p = 0.04, all comparisons). IL-6 levels were higher in the diseased tenocytes as compared with normal tenocytes (44.10 +/- 16.72 versus 0.21 +/- 0.55 ng/ml, (p < 0.05). IL-1 levels in normal cells increased (2.24 +/- 5.02 ng/ml to 9.31 +/- 6.85 ng/ml) after shock wave treatment (p = 0.04). In diseased tenocytes, levels of MMP-1 (1.12 +/- 0.23 to 0.75 +/- 0.24 ng/ml; p = 0.04) and MMP-13 (1.43 +/- 0.11 to 0.80 +/- 0.15 ng/ml; p = 0.04) were significantly decreased after shock wave treatment. The IL-6 level in diseased tenocytes was decreased (44.10 +/- 16.72 to 14.66 +/- 9.49 ng/ml) after shock wave treatment (p = 0.04). CONCLUSION Higher levels of MMPs and ILs were found in human tendinopathy-affected tenocytes as compared with normal cells. ESWT decreased the expression of several MMPs and ILs. CLINICAL RELEVANCE This mechanism may play an important role in shock wave treatment of tendinopathy clinically.

Current concepts review : Orthopaedic aspects of charcot-marie-tooth disease

Charcot-Marie-Tooth (CMT) disease is, in reality, not a single disease, but a group of inheritable defects in the proteins of the peripheral nerve myelin sheath.6 The disorder was first described in 1886 by the French neurologist Jean Martin Charcot and his pupil Marie5 as well as independently by Tooth in England.28 Much like the neuroarthropathy that also bears his name, Charcot’s description of the disease was exhaustive, but his explanation of the pathophysiology was incorrect; he attributed it to a myelopathy. Although Tooth28 described the disease slightly later, he accurately classified it as a peripheral nerve disorder. The nomenclature associated with CMT over the years has been particularly confusing and significantly limits the value of the historical literature on its orthopaedic management. Peroneal muscular atrophy (PMA) was once used as a general term to describe pattern of motor wasting, and the abbreviation appears in the literature even today. Before the current understanding of the genetic underpinnings of the disease, Dyck and Lambert developed an extensive classification of inheritable motor neuropathies based on their electrodiagnostic characteristics.7 They coined the classification of hereditary motor sensory neuropathies I—VII (HMSN IVII). The purpose of this review was to discuss the modern basis for classifying this complex disorder and to review the basis for treatment of its most symptomatic feature: the progressive cavus foot deformity.

Effect of Bupivacaine on Cultured Tenocytes

Proliferation of cultured human fibroblasts and other types of cells has been shown to be hindered by exposure to local anesthetics, which are widely used in musculoskeletal medicine for their use in regional anesthesia, selective nerve blocks, bursography, and brisement. We hypothesized that bupivacaine would decrease cell proliferation and production of extracellular matrix components collagen and proteoglycan in healthy human tenocytes in culture. Primary human tenocyte cultures were prepared from samples of normal tendons obtained from healthy tissue that would otherwise have been discarded during lower extremity tendon transfer surgery. Samples were obtained from 6 patients, 5 women and 1 man with an average age of 69 years (range, 17-73 years). Five flexor digitorum longus tendon samples and 1 peroneus longus tendon sample were used. Harvested tendon tissues (5 mm(3)) were used as explants for primary cell cultures. To measure the proliferative response to bupivacaine, seeded cells were exposed to saline control or to various concentrations of bupivacaine in 1% fetal bovine serum DMEM/F12 or 10% fetal bovine serum DMEM/F12. The 1% fetal bovine serum medium demonstrated the pure bupivacaine effect, and 10% fetal bovine serum more closely approximated the in vivo environment. Seeded cells were starved of fetal bovine serum for 12 hours before exposure to phosphate-buffered saline (control group) and 500 microM bupivacaine (experimental group). This concentration of bupivacaine was selected because it was found to significantly hinder proliferation in both the 1% and 10% fetal bovine serum groups in our proliferation assay. Tenocyte proliferation and extracellular matrix component production were significantly lower (P<or=.05) at >or=1 time points up to 6 days in bupivacaine-treated groups as compared with controls.

Flexor hallucis longus tendon transfer in treatment of Achilles tendinosis.

BACKGROUND In patients with Achilles tendinosis, Achilles tendon debridement can be supplemented with flexor hallucis longus tendon transfer. Outcomes have not been studied prospectively in older, sedentary, and overweight patients. METHODS Fifty-eight consecutive limbs in fifty-six consecutive older, sedentary patients with insertional or midsubstance Achilles tendinosis were enrolled prospectively and underwent the procedure. Ten patients were lost to follow-up, leaving forty-eight limbs in forty-six patients available for evaluation after twenty-four months. RESULTS The forty-six patients who were included in the study had an average age of 54 ± 10 years with an average body mass index of 33.8 ± 6.8 kg/m². Significant improvement was observed between baseline and twenty-four months in terms of the visual analog scale for overall pain intensity (6.7 ± 2.3 versus 0.8 ± 2.0; p < 0.001), the Short Form-36 physical score (34.3 ± 8.0 versus 49.0 ± 9.3; p < 0.001), the Ankle Osteoarthritis Scale pain (54.4 ± 19.2 versus 1.9 ± 2.7; p < 0.001) and dysfunction (62.6 ± 21.4 versus 11.0 ± 24.2; p < 0.001) subscale scores, and performance of a single-leg heel rise (1.9 ± 3.0 versus 7.3 ± 2.7 cm; p < 0.001). Significant improvement compared with baseline was observed at three or six months except in the single-leg heel rise. Improvements in terms of pain and function occurred over twenty-four months, with the most improvement occurring in the first twelve months. At twenty-four months, maximum gastrocnemius circumference was significantly less in the involved compared with the uninvolved leg (40.2 ± 5.1 versus 41.2 ± 4.8 cm; p < 0.001). The mean passive range of motion of the first metatarsophalangeal joint decreased from 85.1° ± 25.3° preoperatively to 68.1° ± 36.7° (a 20% change) at six months (p = 0.03). Most patients reported no hallux weakness (57%; twenty-six of forty-six patients) and no loss of balance due to hallux weakness (76%; thirty-five of forty-six patients). Postoperative peroneal tendinitis was observed in seven patients. Complications included deep-vein thrombosis (two patients), superficial infection or delayed wound-healing (six), scar pain (four), and early disruption of the reconstruction due to a fall (one). CONCLUSIONS Surgical debridement of the Achilles tendon with flexor hallucis longus tendon transfer was associated with significant improvement in terms of Achilles tendon function, physical function, and pain intensity in a group of relatively inactive, older, overweight patients. When present, hallux weakness had minimal functional sequelae.

Endoscopic flexor hallucis longus decompression : A cadaver study

Background New indications for arthroscopy are being considered because arthroscopy limits incision size and potentially decreases operative morbidity. This cadaver study investigated the utility of performing an all-endoscopic flexor hallucis longus (FHL) decompression. Methods Eight fresh-frozen cadaver legs were used. In the simulated prone position with large joint arthroscopic equipment, posterolateral and posteromedial portals were used to perform posterolateral talar process bony excision and FHL sheath debridement and release. We noted the integrity of the sural nerve, FHL tendon, and medial tibial neurovascular bundle. After open dissection, values for sural nerve distance to the posterolateral portal, the amount of FHL sheath released and the proximity of the arthroscopic instrumentation to the medial tibial neurovascular structures were recorded. Results Three of eight FHL tendons were injured during the attempted FHL release. Furthermore, no FHL sheath was completely released down to the level of the sustentaculum. Although posterolateral portal placement was on average 12.1 mm from the sural nerve, it was only 6.1 mm from the lateral calcaneal branch of the sural nerve. Moreover, in all cases the medial calcaneal nerve and first branch of the lateral plantar nerve were closely juxtaposed and in some cases adherent to the FHL fibro-osseous sheath. Conclusions Although os trigonum or posterolateral talar process excision was performed without difficulty, endoscopic release of the FHL tendon proved technically demanding with significant risk to the local neurovascular structures. Given the reliability and low morbidity of open techniques, this cadaver study calls into question the clinical use of complete endoscopic FHL release to the level of the sustentaculum. Moreover, hindfoot endoscopic surgery should be performed by surgeons familiar with open posterior ankle anatomy and experienced in hindfoot endoscopy.

Supplementary axial Kirschner wire fixation for crescentic and Ludloff proximal metatarsal osteotomies: a biomechanical study.

Background: Loss of reduction of proximal metatarsal osteotomies may result from poor bone quality, suboptimal fixation, and limitations inherent in the bony geometry of the osteotomy. This study evaluated the mechanical benefit of adding two supplementary Kirschner wires to the crescentic and Ludloff osteotomies. Methods: Eleven and 10 matched pairs of cadaver foot specimens were used for the Ludloff and the proximal crescentic metatarsal osteotomies, respectively. Each metatarsal head specimen was then loaded to failure using a servohydraulic MTS Mini Bionix test frame (MTS Systems Corp, Eden Prairie, MN), and the failure gap was measured with an extensometer. To account for variable bone quality in the study specimens, the failure loads were normalized with the measured bone mineral density (BMD) values of the metatarsal specimens. A paired Students t-test analysis was used to compare the failure loads between the specimens with the conventional osteotomies and the osteotomies supplemented with two axial Kirschner wires. Results: The load-to-failure of the Ludloff osteotomy with two screws and with one proximal screw and two Kirschner wires was 858.5 N cm 2 /gm and 692.3 N cm 2 /gm, respectively (p > 0.05). The average load-to-failure of crescentic osteotomy with one screw and two axial Kirschner wires (458.8 N cm 2 /gm) was significantly higher than the strength of crescentic osteotomy fixed with one screw only (367.5 N cm 2 /gm) (p = 0.05). For the Ludloff osteotomy, 16 specimens (72.7%) failed by more than 2 mm of gapping. The crescentic osteotomy failures included 16 2-mm gap failures (80%). The Ludloff osteotomy showed a trend toward increased fixation stability as compared with both crescentic osteotomy constructs. Conclusion: The use of two supplemental axial Kirschner wires offers a simple and effective means to improve the initial mechanical stability of the proximal crescentic osteotomy and can be used in the standard Ludloff osteotomy to replace the second screw when screw purchase is poor without significant loss of fixation strength. The possible advantage of Kirschner wire flexibility in restoring position after gapping of the osteotomy site should be investigated.

ATFL elongation after Brostrom procedure: a biomechanical investigation.

Background: Elongation of ligaments during early mobilization after reconstruction may be associated with decreased stability. We evaluated elongation of the anterior talofibular ligament (ATFL) before and after lateral ligament reconstruction within a physiologic range of motion with protected and unprotected, isolated dorsiflexion/plantarflexion range of motion. Materials and Methods: Six fresh frozen cadaver legs were used with the ATFL meticulously dissected. A differential variable reluctance transducer (DVRT) was spaced to span the course of the ATFL using consistent placement points based on previous reports. Elongation was measured in a load frame with protected motion of 30 degrees plantarflexion and 10 degrees dorsiflexion for the intact and sectioned ATFL and for the repaired specimen with and without protected motion. The proximal DVRT anchor point was detached for sectioning and repair of the ATFL and replaced at the same position. Testing was 1000 cycles at 1 Hz for the repaired protected specimen and 10 cycles at 1 Hz for all other stages. Results: Initial elongation in the unprotected, repaired group was significantly higher than initial elongation in the intact (p < 0.01), sectioned (p = 0.02), and repaired, protected (p < 0.01) groups. Final elongation in the unprotected repaired group was also higher than final elongation in all other groups (p < 0.01 for all comparisons). Conclusion: The use of protected range of motion of the ankle after lateral ankle ligament reconstruction was not associated with elongation of the ATFL. The ATFL elongated significantly by comparison without protected dorsiflexion/plantarflexion. Clinical Relevance: The study provides biomechanical support for the safety of early protected dorsiflexion/plantarflexion range of motion after Broström reconstruction.