Biomedical subjects

Michael S Aronow

Publications and source records attributed to Michael S Aronow.

11 recordsLinked to original sources

PubMed2006

Treatment of the missed Lisfranc injury.

Lisfranc joint injuries may be missed at the time of occurrence potentially leading to persistent instability, deformity, or arthritis. In the absence of significant residual arthritis or fixed deformity, delayed open reduction and internal fixation with or without reconstruction of the Lisfranc ligament may be performed. An alternative is reduction and primary arthrodesis of the relatively immobile medial tarsometatarsal (TMT) joints. In the presence of significant residual arthritis or fixed deformity that is recalcitrant to conservative treatment, arthrodesis, including correction of deformity, is the treatment of choice for the first, second, and third TMT joints. Resection arthroplasty of the fourth and fifth TMT joints may be preferable to arthrodesis in order to maintain physiologic motion.

Diagnostic Errors↗

PubMed2006

The effect of triceps surae contracture force on plantar foot pressure distribution.

BACKGROUND: Triceps surae contractures have been associated with foot and ankle pathology. Achilles tendon contractures have been shown to shift plantar foot pressure from the heel to the forefoot. The purpose of this study was to determine whether isolated gastrocnemius contractures had similar effects and to assess the effects of gastrocnemius or soleus contracture on midfoot plantar pressure. METHODS: Ten fresh frozen cadaver below-knee specimens were loaded to 79 pounds (350 N) plantar force with the foot unconstrained on a 10-degree dorsiflexed plate. Combinations of static gastrocnemius or soleus forces were applied in 3-lb increments and plantar pressure recordings were obtained for the hindfoot, midfoot, and forefoot regions. RESULTS: The percentage of plantar force borne by the forefoot and midfoot increased with triceps surae force, while that borne by the hindfoot decreased (p<or=0.005). Increasing gastrocnemius force had similar results. Increasing triceps surae force from 0 to 21 lbs (93 N) increased average percent forefoot and midfoot force 59% and 38%, respectively, and reduced average percent hindfoot force 18%. Increasing gastrocnemius force from 0 to 18 lbs increased average percent forefoot and midfoot force 50% and 32%, respectively, and reduced average percent hindfoot force 16%. For a given triceps surae force, there was no statistical difference in pressure distribution noted between different combinations of gastrocnemius and soleus force. CONCLUSIONS: In a static model, increased triceps surae or isolated gastrocnemius force shifted weightbearing plantar pressure from the hindfoot to the midfoot and forefoot. Similar results were noted whether the triceps surae force was applied through the gastrocnemius or soleus or both. The results of this study are consistent with the clinical association of triceps surae contracture with foot and ankle disorders including diabetic foot ulcers and metatarsalgia. The similar effects with triceps surae force application through the gastrocnemius or soleus suggest that patients with isolated gastrocnemius contractures may obtain similar clinical benefits with potentially less morbidity after gastrocnemius aponeurosis lengthening as compared to Achilles tendon lengthening.

Achilles Tendon↗

PubMed2006

An in vitro study comparing the use of suture anchors and drill hole fixation for flexor digitorum longus transfer to the navicular.

BACKGROUND: The surgical management of posterior tibial tendon dysfunction often includes transfer of the flexor digitorum longus (FDL) tendon through a tunnel in the navicular. Fixation often is obtained by sewing the tendon back onto itself. The purpose of this study was to compare this standard method of fixation with suture anchor fixation, a technique that may be associated with less surgical morbidity, because it requires the harvesting of less tendon length. METHODS: FDL tendon transfer to the navicular was done in 13 fresh-frozen cadaver specimens. In six feet comprising the standard group, the FDL tendon was transected distal to the master knot of Henry, placed through a drill hole into the navicular, and sutured back onto itself. In seven feet the FDL tendon was transected proximal to the master knot of Henry, placed into a drill hole into the navicular, and fixed with a suture anchor. Load was applied to the proximal FDL muscle and tendon using a materials testing system (MTS) machine and peak load to failure was measured. RESULTS: The mean load to failure was 142.48 N +/- 38.06 N for the standard group and 142.12 N +/- 59.26 N for the suture anchor group (p = 0.305 for the Student-t test and p = 0.945 for the Mann-Whitney test). CONCLUSION: Transfer of the FDL tendon to the navicular using suture anchor fixation requires less tendon length yet provides similar fixation strength as compared to sewing the tendon back onto itself. However, suture anchors are considerably more expensive than sutures. CLINICAL IMPLICATIONS: Suture anchors allow comparable fixation of FDL tendon transfer into a navicular without the need to disrupt the master knot of Henry. This technique may be associated with less morbidity including a shorter incision, decreased risk of medial plantar nerve injury, and decreased loss of lesser toe plantarflexion strength secondary to maintenance of the normal interconnections between the flexor hallucis longus (FHL) and FDL tendons.

Cadaver↗

PubMed2006

Cyclic loading of Achilles tendon repairs: a comparison of polyester and polyblend suture.

BACKGROUND: Early functional rehabilitation is widely used after open suture repair of the Achilles tendon. To our knowledge, no previous studies have assessed gap formation from cyclic loading and subsequent failure loads of simulated Achilles tendon repairs. A synthetic (polyblend) suture has been introduced for tendon repairs with reportedly greater strength than polyester suture. This stronger, stiffer suture material may provide stronger repairs with less elongation of the tendon repair. METHODS: Simulated Achilles tendon ruptures in bovine Achilles tendon were repaired with a four-strand Krackow suture technique using No. 2 polyester suture. Specimens were loaded for 3,000 cycles at maximal loads of 50, 75, 100, or 125 N, and gap formation at the repair site was continuously measured. After cyclic loading, each specimen was loaded to failure. Identical repairs were performed with number 2 polyblend suture and cyclically loaded to 75 N for 3,000 cycles. All specimens were loaded to failure. RESULTS: Cyclically loading polyester suture repairs to 50, 75, 100, or 125 N for 3,000 cycles resulted in mean gapping at the repair site of 3.0 +/- 0.8, 4.9 +/- 1.0, 7.2 +/- 0.9, and 7.9 +/- 0.8 mm, respectively. Cyclically loading the polyblend suture repairs for 3,000 cycles at 75 N, resulted in 3.3 +/- 0.3 mm of gap formation at the repair site, significantly less than polyester suture repairs (p < 0.001). The mean load to failure for polyester suture repair was 222 +/- 19 N and for polyblend suture repair was 582 +/- 49 N, a statistically significant difference (p < 0.001). Gap formation at 100, 1,000, and 2,000 cycles, as a percentage of total gap formation at 3,000 cycles, was 64.3%, 87.5%, and 95.4% for polyester suture and 45.8%, 78.5%, and 90.1% for polyblend repairs. All specimens in all groups failed at the knots during load-to-failure testing. CONCLUSIONS: Cyclic loading of simulated Achilles tendon repairs using a Krackow, four-core polyester suture technique showed progressive gap formation with increasing load. All repairs failed at the knot, and suture pull-out from tendon was not observed. Polyblend suture repair, when compared to identical repairs with braided polyester suture, resulted in a 260% higher load to failure and 33% less gap formation at the repair site after 3,000 cycles. CLINICAL RELEVANCE: The use of polyblend suture in a four-stranded Krackow configuration provides stronger repairs with less gap formation, which may provide increased security during early functional rehabilitation.

Achilles Tendon↗

PubMed2005

Transforming growth factor-beta 1 (TGF-beta1) prevents the age-dependent decrease in bone formation in human osteoblast/implant cultures.

Titanium implants have been extensively used in orthopedic surgery and dentistry. Most of the patients who receive such implants are elderly with a compromised ability to heal and form new bone. By using an in vitro osteoblast/implant culture system, the potency of TGF-beta1 in enhancing mineralization of human osteoblast cultures from elderly subjects was investigated in this study. Primary human osteoblast (HOB) cells obtained from different age group human subjects [Young (Y), Middle (M), and Old (O)] were cultured on Ti alloy (Ti-6Al-4V) disks with or without continuous administration of 0.2 ng/mL TGF-beta1 in the medium for 2 or 4 weeks. TGF-beta1 significantly (p < 0.05) increased calcium content and the size of calcified nodules on implant disks in the O group, but had no effect on the Y or M groups. The number of calcified nodules was not different with or without TGF-beta1 in all age groups. As measured by Northern blot analysis and RT-PCR, TGF-beta1 significantly increased the expression of bone-specific extracellular matrix proteins, including alkaline phosphatase, Type I collagen, bone sialoprotein and osteocalcin, after both 2 and 4 weeks in the O group but not in the Y group. In conclusion, TGF-beta1 enhances mineralization on implant materials of osteoblast cultures from elderly human subjects.

Absorbable Implants↗

PubMed2005

Posterior heel pain (retrocalcaneal bursitis, insertional and noninsertional Achilles tendinopathy).

The majority of patients with Achilles tendinopathy respond to nonoperative treatment. In patients with refractory symptoms, surgery can be considered. If paratenonitis is present, the paratenon is partially excised, and adhesions are released. Areas of symptomatic tendinosis are excised with repair of the residual defect in the Achilles tendon. An alternative for patients with tendinosis who are at increased risk for wound problems or who do not want a large open incision is percutaneous or endoscopic tenotomy. A symptomatic Haglund's deformity or inflamed retrocalcaneal bursa is excised. Augmentation of the Achilles tendon may be considered if debridement threatens the structural integrity of the tendon, in older patients, and in revision surgery.

Achilles Tendon↗

PubMed2005

Ligamentous Lisfranc joint injuries: a biomechanical comparison of dorsal plate and transarticular screw fixation.

BACKGROUND: The current treatment of displaced ligamentous injuries of the tarsometatarsal (TMT) joints is open reduction and rigid fixation using transarticular screws. This technique causes further articular surface damage that theoretically may increase the risk of arthritis. Should the screws break, hardware removal is difficult. An alternative method that avoids these potential complications is rigid fixation using dorsal plates. METHODS: The displacement between the first metatarsal and medial cuneiform, the second metatarsal and intermediate cuneiform, the first and second metatarsal bases, and the medial cuneiform and second metatarsal base were measured in 10 matched pairs of fresh-frozen cadaver lower extremities in the unloaded and loaded condition. After sectioning the Lisfranc and TMT joint ligaments, measurements were repeated in the loaded condition. The first and second TMT joints of the right feet were fixed with transarticular 3.5-mm cortical screws while those of the left feet with were fixed with dorsal 2.7-mm 1/4 tubular plates. Measurements were then repeated in the unloaded and loaded condition. RESULTS: After ligament sectioning, significantly increased first and second TMT joint subluxation with loading was seen. No significant difference was noted with direct comparison between plates and screws with respect to ability to realign the first and second TMT joints and to maintain TMT joint alignment during loading. The amount of articular surface destruction caused by one 3.5-mm screw was 2.0 +/- 0.7% for the medial cuneiform, 2.6 +/- 0.5% for the first metatarsal, 3.6 +/- 1.2% for the intermediate cuneiform, and 3.6 +/- 1.0% for the second metatarsal. CONCLUSIONS: The model reliably produced displacement of the first and second TMT joints consistent with a ligamentous Lisfranc injury. Transarticular screws and dorsal plates showed similar ability to reduce the first and second TMT joints after TMT and Lisfranc ligament transection and to resist TMT joint displacement with weightbearing load. CLINICAL RELEVANCE: Dorsal plating may be an alternative to transarticular screws in the treatment of displaced Lisfranc injuries.

Biomechanical Phenomena↗

PubMed2004

The effects of patient age on human osteoblasts' response to Ti-6Al-4V implants in vitro.

Osseointegrated implants are a common therapy for the elderly population as lifespan increases. Understanding the effects of age and sex on osseointegration is important for successful implant therapy. Therefore, the response of primary human osteoblasts (HOB) to implant materials was studied. HOBs were obtained by outgrowth of cells from bone from orthopaedic procedures and categorized as Young (Y), <15; Middle (M), 30-50; and Old (O), >60 years old. Initially the HOB phenotype was determined on tissue culture plastic. Alkaline phosphatase (ALP) staining and activity were significantly increased in HOBs from older patients. Message levels of type I collagen (COL), bone sialoprotein (BSP) and ALP were significantly higher (from 2.3- to 3.8-fold) in Y subjects compared to M and O patients at 2 weeks. Studies of the response of HOBs to implant materials were undertaken using Ti-6Al-4V disks prepared in a manner similar to orthopaedic implants. A 1.4-fold (p<0.05) increase in cell attachment was found in HOBs from Y compared with O in female subjects but not in male subjects. Cell proliferation at 24 h was not significantly different by age or sex, nor was DNA content different at 2 and 4 weeks. Mineralization in HOB-implant cultures was 2.3-fold higher in Y than in O, and 1.7-fold higher in Y compared to M HOBs from female but not male subjects at 4 weeks. Northern blot and RT-PCR analysis at 2 weeks of culture showed significantly higher levels (1.6-2.3-fold) of COL, BSP, and osteocalcin (OC) mRNAs in Y HOBs compared to M and O HOBs from female subjects. We conclude that human osteoblasts from older female patients have a decreased ability to form bone on implants.

Adult↗

PubMed2003

Foot and ankle experience in orthopaedic residency.

BACKGROUND: Dedicated orthopaedic residency training in the musculoskeletal discipline of foot and ankle is an important contribution to the development of a well-rounded orthopaedic surgeon. Current residency training guidelines are vague and do not require specific experience or proficiency in this discipline. METHODS: A one-page questionnaire on commitment to foot and ankle education in American Orthopaedic Surgery residency training programs was completed by all 148 program directors. RESULTS: Eighty of the programs (54.1%) had a single faculty member dedicated to foot and ankle orthopaedics, while 21 (14.2%) did not have a faculty member with a specific interest or commitment to problems related to the foot and ankle. Fifteen programs (10.1%) did not have a committed faculty member, nor did their residents have a clinical rotation dedicated to foot and ankle. Ninety-six programs (64.9%) had at least one clinical rotation dedicated to foot and ankle. Fifty-two (35.1%) did not. Thirty-three (34.7%) of those programs with a dedicated foot and ankle experience assigned residents during at least two periods of their training. Of those programs with a single foot-specific rotation, the most common year for training was in the PGY3 year (27 of 63, 42.9%). Of the 60 months' duration of most orthopaedic residency programs, 39 of 96 (40.6%) programs with a dedicated clinical foot and ankle rotation allocated an average of 12 weeks to foot and ankle. Twenty-six (27.1%) allocated less than 3 total months, and 31 (32.3%) allocated 16 to 24 weeks of dedicated foot and ankle experience. CONCLUSIONS: Current residency training in the United States does not universally require a commitment to foot and ankle education. A large number of residency programs do not have a faculty member committed to foot and ankle education, and almost one-third have no time specifically allocated to foot and ankle education.

Ankle↗

PubMed2002

Different faces of the triple arthrodesis.

Patients with severe pes planovalgus or cavovarus foot deformities who fail conservative treatment may require a triple arthrodesis. Modifying the triple arthrodesis to include extended bone wedge resections allows for improved correction. The goal of each procedure is to obtain a less painful, plantigrade foot, and to improve function. Additional hindfoot or midfoot osteotomies may be needed in the modified triple arthrodesis. Midfoot or forefoot cavus can be addressed with either the Japas, Cole, or Jahss osteotomies, as described above. Residual hindfoot valgus can be adequately corrected with a medial displacement osteotomy of the calcaneus. Residual hindfoot varus is preferably corrected through a lateral closing wedge calcaneal osteotomy. This allows for adequate correction without the need for bone graft or an extended medial incision in the area of the tibial neurovascular bundle. Good results have been obtained with these types of complicated reconstructive procedures.

Arthrodesis↗

PubMed2002

Adolescent osteochondral lesion of the talus. Ankle arthroscopy in pediatric patients.

Osteochondral lesions of the talus can be difficult to diagnose and can result in a significant functional limitation in young, active patients. New imaging modalities have improved the diagnosis and staging of these lesions. In general, nonoperative treatment results in poorer outcomes compared with operative treatment, and arthroscopic treatment has results similar to open treatment. Although the literature is limited, the treatment of adolescents results in outcomes similar to the adult population.

Adolescent↗