Corrective Osteotomy for Symptomatic Radial Head and Neck Malunions in the Skeletally Immature.

BACKGROUND: Radial head and neck fracture malunion can lead to pain, stiffness, deformity, and functional limitations. This study analyzed the early radiographic and functional outcomes of corrective osteotomy for symptomatic radial head and/or neck malunion in skeletally immature patients. METHODS: Thirteen pediatric patients treated with corrective osteotomy for symptomatic radial head and/or neck malunion from 2004 to 2018 were identified. Radiographic union, range of motion, pain, and complications were recorded. Functional outcomes were assessed using the Broberg and Morrey Elbow Scale. RESULTS: The average age at the time of surgery was 12.3 years (range: 8.6 to 16.3). The mean time from injury to osteotomy was 7.5 months (range: 2 to 24.1 mo). Before osteotomy, mean radial head-shaft angulation was 23 degrees (range: 5 to 57 degrees), mean displacement was 76% (range: 0 to 55), average elbow flexion contracture was 18 degrees (range: 0 to 60 degrees), and average elbow flexion was 112 degrees (range: 95 to 135 degrees). After a mean follow-up of 14.3 months, 12 of 13 osteotomies (92%) healed; 1 patient had a painless nonunion. The number of patients reporting pain decreased from 9 to 2 ( P =0.012). Radiographic alignment and range of motion improved in all patients. Mean angulation and displacement improved to 8 degrees (range: 2 to 15 degrees, P =0.001) and 3% (range: 0 to 18 degrees, P =0.001), respectively. Mean elbow flexion contracture was reduced to 5 degrees (range: 0 to 30 degrees, P =0.008), and the average elbow flexion increased to 128 degrees (range: 100 to 135 degrees, P <0.001). Three patients underwent implant removal for complications, including heterotopic ossification and avascular necrosis. Physeal arrest did not lead to any adverse sequelae. The sole case of avascular necrosis had a reduced range of motion but no pain. The mean postoperative Broberg and Morrey score was 91.1; 7 patients had excellent postoperative scores, 4 good, and 2 fair. CONCLUSIONS: Corrective osteotomy for symptomatic malunion of the radial head and/or neck in skeletally immature patients can improve elbow alignment, motion, pain, and function. Preservation of the soft-tissue attachments to the proximal epiphysis and rigid internal fixation are critical components of this surgical technique. LEVEL OF EVIDENCE: Therapeutic Level IV.

Digit Replantation The First 50 Years.

Since the first successful digit replantation by Japanese surgeons Komatsu and Tamai, the past half century has seen the field of digit replantation in the USA experience exponential growth followed by a steady decline in volume of cases and percentage of successful viable digits. The initial enthusiasm and technical progress of digital replantation has been tempered by mediocre functional outcomes, rising healthcare costs, and limited healthcare resources. The history and approach to digit replantation is reviewed and highlights the likely push toward the development of regional replant centers staffed by highly skilled teams to improve the functional outcomes following these complex procedures. More than 50 years have passed since the first successful digit replantation by Komatsu and Tamai who replanted a sharply amputated thumb in a 28-year-old male at the metacarpal-phalangeal joint level in a 4.5 hour procedure. Two arteries and 2 veins were anastomosed using 8-0 monofilament nylon and 7-0 braided silk suture. The patient remained in the hospital for 40 days and did not return to work for 4 months. News of this triumph of microvascular skill was heralded throughout the world as the first successful replantation of a completely amputated digit. Over the past half century, the field of digit replantation in the USA experienced exponential growth followed by a steady decline in volume of cases and percentage of successful viable digits. The initial enthusiasm and technical progress of digital replantation has been tempered by mediocre functional outcomes, rising healthcare costs, and limited healthcare resources. In the next 50 years, it is possible that the majority of digit replantation procedures in the USA may be performed in tertiary centers or regional replant centers by highly skilled teams.

Biomechanical evaluation of 5 fixation devices for proximal interphalangeal joint arthrodesis.

PURPOSE: To determine in a cadaver model which, among 5 fixation methods for proximal interphalangeal (PIP) joint arthrodesis, has the greatest stiffness. METHODS: Thirty-five cadaver digits were randomly assigned to 1 of 5 fixation groups: oblique K-wire with coronal intraosseous wiring, tension-band wire (TBW), dorsal plate, intramedullary linked screw (IMS), and 90/90 wiring (90/90W). Testing was done by applying bending moments to the PIP joint in the sagittal and frontal planes. The force/displacement curves were used to estimate the stiffness of each construct. Ultimate strength was determined by loading to failure in extension. RESULTS: The IMS had significantly higher stiffness than all wiring constructs in all planes of motion and significantly greater stiffness in extension than the dorsal plate. The IMS stiffness exceeded 10 N/mm across all bending directions and showed an ultimate strength of 21 N. The plate demonstrated higher stiffness in radial bending than the oblique K-wire with coronal intraosseous wiring and TBW. There were no differences in stiffness between the IMS and plate in all modes of testing except extension. Load-to-failure testing of the devices showed the IMS device to be significantly stronger than the TBW, 90/90W, and plating constructs. CONCLUSIONS: The IMS resisted larger bending moments than all wiring constructs and showed the greatest ultimate strength when compared with 3 of the tested arthrodesis techniques. The plate was significantly better than 2 of the wiring constructs, but only in radial bending. No differences were found between the, TBW, and 90/90W when compared with each other. CLINICAL RELEVANCE: The stiffness necessary for a successful PIP joint fusion has not been quantified, but according to this study, the IMS was the most favorable biomechanical construct for initial stability.

Maternal high-altitude hypoxia and suppression of ryanodine receptor-mediated Ca2+ sparks in fetal sheep pulmonary arterial myocytes.

Ca(2+) sparks are fundamental Ca(2+) signaling events arising from ryanodine receptor (RyR) activation, events that relate to contractile and dilatory events in the pulmonary vasculature. Recent studies demonstrate that long-term hypoxia (LTH) can affect pulmonary arterial reactivity in fetal, newborn, and adult animals. Because RyRs are important to pulmonary vascular reactivity and reactivity changes with ontogeny and LTH we tested the hypothesis that RyR-generated Ca(2+) signals are more active before birth and that LTH suppresses these responses. We examined these hypotheses by performing confocal imaging of myocytes in living arteries and by performing wire myography studies. Pulmonary arteries (PA) were isolated from fetal, newborn, or adult sheep that lived at low altitude or from those that were acclimatized to 3,801 m for > 100 days. Confocal imaging demonstrated preservation of the distance between the sarcoplasmic reticulum, nucleus, and plasma membrane in PA myocytes. Maturation increased global Ca(2+) waves and Ca(2+) spark activity, with sparks becoming larger, wider, and slower. LTH preferentially depressed Ca(2+) spark activity in immature pulmonary arterial myocytes, and these sparks were smaller, wider, and slower. LTH also suppressed caffeine-elicited contraction in fetal PA but augmented contraction in the newborn and adult. The influence of both ontogeny and LTH on RyR-dependent cell excitability shed new light on the therapeutic potential of these channels for the treatment of pulmonary vascular disease in newborns as well as adults.

Measurement of the incorporation and repair of exogenous 5-hydroxymethyl-2'-deoxyuridine in human cells in culture using gas chromatography-negative chemical ionization-mass spectrometry.

The DNA of all organisms is constantly damaged by oxidation. Among the array of damage products is 5-hydroxymethyluracil, derived from oxidation of the thymine methyl group. Previous studies have established that HmU can be a sensitive and valuable marker of DNA damage. More recently, the corresponding deoxynucleoside, 5-hydroxymethyl-2'-deoxyuridine (HmdU), has proven to be valuable for the introduction of controlled amounts of a single type of damage lesion into the DNA of replicating cells, which is subsequently repaired by the base excision repair pathway. Complicating the study of HmU formation and repair, however, is the known chemical reactivity of the hydroxymethyl group of HmU under conditions used to hydrolyze DNA. In the work reported here, this chemical property has been exploited by creating conditions that convert HmU to the corresponding methoxymethyluracil (MmU) derivative that can be further derivatized to the 3,5-bis-(trifluoromethyl)benzyl analogue. This derivatized compound can be detected by gas chromatography-negative chemical ionization-mass spectrometry (GC-NCI-MS) with good sensitivity. Using isotopically enriched exogenous HmdU and human osteosarcoma cells (U2OS) in culture, we demonstrate that this method allows for the measurement of HmU in DNA formed from the incorporation of exogenous HmdU. We further demonstrate that the addition of isotopically enriched uridine to the culture medium allows for the simultaneous measurement of DNA replication and repair kinetics. This sensitive and facile method should prove valuable for studies on DNA oxidation damage and repair in living cells.