Vascularized Growth Plate Transfer in Paediatric Ulna Non-Union: Operative Technique and Review of the Literature.

Congenital pseudarthrosis of forearm fractures is rare and is strongly associated with neurofibromatosis type 1 (NF1). Our case report illustrates the progression of a non-union of the ulna after minor trauma in a twelve-year-old boy, newly diagnosed with NF1, and presents the technique of microsurgical bone reconstruction, including the growth plate. More than seven years after the first operation, follow-up presents a favorable outcome with a pain-free patient and unrestricted function of the forearm after a secondary correction of the remaining radial bowing. This treatment is discussed with a comprehensive review of the current literature on ulnar congenital pseudarthrosis in PubMed and Google Scholar and free fibular growth plate transfer in PubMed and Google Scholar. Nine publications reporting on 20 cases of congenital ulnar non-unions were identified. With this reconstructive option, favorable outcomes were achieved in all cases with the union after primary surgery and complications requiring further surgeries in nine cases. The benefit of vascularized growth plate bone transfer in congenital ulna non-union seems to be significant compared to other therapies such as open reduction internal fixation (ORIF), non-vascularized bone grafts, or one-bone-forearms and beneficial when growth reconstruction is needed. Other techniques might be necessary to improve insufficient long-term results.

Arteriovenous Loops Enable Free Tissue Transfer With Otherwise Inadequate Local Donor and Recipient Vessels.

BACKGROUND/AIM: Free flap reconstruction with damaged or diseased vessels is a challenging problem. We describe our case series using an arteriovenous loop or bypass surgery with free flaps for complex defect reconstructions at the lower extremity and the pelvic region. PATIENTS AND METHODS: In this single-center retrospective cohort study 11 consecutive patients (mean age=73 years, range=53-88 years) were operated on, between June 2016 and August 2018. Patients were reconstructed with free gracilis flaps (n=8), free latissimus dorsi flap (n=1) and chimeric scapular flap (n=1), respectively. RESULTS: The mean loop length was 30 cm (range=12-40 cm). The loop/bypass revision rate was 27% (3/11), and the overall flap loss rate was 20% (2/10). After a mean follow-up time of 17 months (range=12-24 months), the limb salvage rate was 75% (6/8). CONCLUSION: We successfully reconstructed complex defects with poor recipient vessels using arteriovenous loops or bypass surgery and free flaps.

Can the American College of Surgeons NSQIP surgical risk calculator identify patients at risk of complications following microsurgical breast reconstruction?

INTRODUCTION: The American College of Surgeons National Surgery Quality Improvement Program (ACS NSQIP) Surgical Risk Calculator is an open access online tool that estimates the risk of adverse post-operative events for a wide range of surgical procedures. This study evaluates the predictive value of the ACS NSQIP calculator in patients undergoing microvascular breast reconstruction. STUDY DESIGN: Details of 759 microvascular breast reconstructions in 515 patients were entered into the online calculator. The predicted rates of post-operative complications were recorded and compared to observed complications identified on chart review. The calculator was validated using three statistical measures described in the original development of the ACS NSQIP model. RESULTS: The calculator predicted that complications would occur in 11.1% of breast reconstructions while the observed rate was 10.5%. Hosmer-Lemeshow test did not find any statistical difference between these rates (p = 0.69) indicating that the calculator accurately measured what is was intended to measure. The area under the receiver operating curve or c-statistic (measure of discrimination) was found to be low at 0.548, indicating the model has random performance in this patient population. The Brier score was higher than that reported in the original ACS calculator development (0.094 vs 0.069) demonstrating poor correlation between predicted probability and actual probability. CONCLUSIONS: This study demonstrates that while the ACS NSQIP Universal risk calculator can predict the proportion of patients that will develop complications it cannot effectively discriminate between patients who are at risk of complications and those who are not.

Restrictive use of perioperative blood transfusion does not increase complication rates in microvascular breast reconstruction.

INTRODUCTION: With increasing appreciation of the possible adverse effects of peri-operative blood transfusion, restrictive policies regarding use of blood products have been adopted in many surgical specialties. Although microvascular breast reconstruction has become a routine procedure, high peri-operative transfusion rates continue to be reported in the literature. In this study we examine the impact of our restrictive approach on blood transfusion rates and postoperative complications in patients undergoing microvascular blood transfusion. METHODS: A retrospective review of patients undergoing microvascular breast reconstruction with abdominal flaps at a single institution was performed. Patient age and body mass index as well as type, timing and laterality of reconstruction was recorded. Pre-operative and post-operative hemoglobin and hematocrit were recorded. Peri-operative blood transfusion rates were calculated. Post-operative complication rates were compared between patients with higher and lower post-operative hemoglobin levels. RESULTS: Five hundred and twelve patients were included in this study. The peri-operative transfusion rate was 0.98% in this series. There was no significant difference between transfusion rates in unilateral and bilateral reconstructions (0.68 vs 1.36% p = 0.08) or immediate and delayed reconstructions (1.02 vs 0.51% p = 0.72 and 1.01 vs 1.60% p = 0.09 for unilateral and bilateral respectively). Lower post-operative hemoglobin levels were not associated with increased flap related, surgical or medical complications rates. CONCLUSION: A restrictive approach to peri-operative blood transfusion can be safely adopted in microvascular breast reconstruction without compromising flap viability or overall complication rates.

Generation and characterization of osteochondral grafts with human nasal chondrocytes.

We investigated whether nasal chondrocytes (NC) can be used to generate composite constructs with properties necessary for the repair of osteochondral (OC) lesions, namely maturation, integration and capacity to recover from inflammatory burst. OC grafts were fabricated by combining engineered cartilage tissues (generated by culturing NC or articular chondrocytes - AC - onto Chondro-Gide® matrices) with devitalized spongiosa cylinders (Tutobone®). OC tissues were then exposed to IL-1ß for three days and cultured for additional 2 weeks in the absence of IL-1ß. Cartilage maturation extent was assessed (immune) histologically, biochemically and by delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) while cartilage/bone integration was assessed using a peel-off mechanical test. The use of NC as compared to AC allowed for more efficient cartilage matrix accumulation and superior integration of the cartilage/bone layers. dGEMRIC and biochemical analyzes of the OC constructs showed a reduced glycosaminoglycan (GAG) contents upon IL-1ß administration. Cartilaginous matrix contents and integration forces returned to baseline up on withdrawal of IL-1ß. By having a cartilage layer well developed and strongly integrated to the subchondral layer, OC tissues generated with NC may successfully engraft in an inflammatory post-surgery joint environment.

Fatigue-related decrease in Piper rhythm frequency of the abductor pollicis brevis muscle during isometric contractions.

The purpose of this study was to analyze how the frequency of the Piper rhythm of the abductor pollicis brevis muscle (APB) and thus of the rhythmic synchronization of motor units changes with fatigue. Fourteen subjects participated in the study. The EMG signals were measured during maximum voluntary contractions, and a mimicked motor unit action potential was used to simulate an EMG signal containing no rhythmicity. The simulated EMG was used as a reference. The Piper rhythm was extracted from the high frequency power (170-271 Hz) of the wavelet transformed real and simulated EMG data using the difference of the autocorrelation functions of the power. The study shows that the Piper rhythm of the APB muscle, its pacing frequency and pacing amplitude can be extracted from the EMG signal recorded during a fatiguing task. One can conclude that the pacing frequencies observed in various hands covered the whole frequency range of the Piper band which includes the beta and the gamma band frequencies observed in brain activity (17-60 Hz). While the pacing frequency decreased with fatigue the pacing amplitude did not change significantly. The Piper rhythm is a result of a changing central drive and its measurement thus allows observing changes of central drive to the muscle. The ability to better resolve the Piper rhythm in the EMG without using the coherence with the brain activity opens the possibility to study the behavior of central control in the peripheral signal.

Piper rhythm of the electromyograms of the abductor pollicis brevis muscle during isometric contractions.

A temporal pattern coding, synchronization and rhythmicity form an integral part of central nervous system information controlling the muscle activation. Rhythmic oscillations of muscles at frequencies of 35-60 Hz were already noted in the electromyograms by Piper (1907). The purpose of this study was to resolve the Piper rhythm in the EMG of the APB muscle and report the pacing frequencies of the Piper rhythm. The Piper rhythm was identified using the power of the EMG signals extracted by a wavelet transform at higher frequencies (170-271 Hz). The results showed distinct power of the intensity extracted by the wavelets in a frequency band ranging from about 30-60 Hz. The band was reflected in the power spectra of the EMG intensity and in the first eigenvector of a principal component analysis of the power spectra. The fact that the Piper rhythm shown in this study for the APB muscle yielded a large contribution to the total power means that one can use the frequency and amplitude of the Piper rhythm in future analysis of EMG signals to monitor the influence and changes of the central command.

Wavelet based correlation and coherence analysis reveals frequency dependent motor unit conduction velocity of the abductor pollicis brevis muscle.

The purpose of this study was to investigate the motorunit conduction velocity (CV) as a function of frequency. A wavelet based correlation and coherence analysis was introduced to measure CV as a function of frequency. Based on the most simple assumption that the power spectra of the motor unit action potential is shifted to higher frequencies with increasing CV, we hypothesized that there would be a monotonic or linear trend of increasing CV with frequency. This trend was only confirmed at higher frequencies. At lower frequencies the trend was often reversed leading to a decrease in CV with increasing frequency. Thus the CV was high at low frequencies, went through a minimum at about 170 Hz and increased at higher frequencies, as expected. The observed CV at low frequencies could not be fully explained by assuming non-propagating signals or variable groups of motor units. We concluded that spectra and CV contain partly independent information about the muscles and that the wavelet based method provides the tools to measure them both simultaneously.

Frequency and conduction velocity analysis of the abductor pollicis brevis muscle during early fatigue.

The physiological behavior of the abductor pollicis brevis (APB) muscle during early stage of fatigue is important as a reference for future clinical assessment of a pathologically altered muscle, as e.g. in carpal tunnel syndrome. The purpose of this study was to assess changes of force and surface electromyograms (sEMG) during early stage of fatigue of the APB. Thumb abduction force and sEMG derived from a multi-electrode array were recorded during isometric contraction. Electrode placement over the innervation zone (IZ) and the muscle tendon interface were avoided. The sEMGs of two adjacent electrode pairs were selected for the analysis, which yielded (a) motor unit conduction velocities (MUCV) derived from a correlation analysis between the EMGs and (b) mean frequencies obtained by using either fast Fourier (FMF) or Wavelet Transform (WMF). Early fatigue resulted in a relative decay rate of force (-2.1%( *)s(-1)), MUCV (-1.5%( *)s(-1)), FMF (-4.1%( *)s(-1)), WMF (-3.7%( *)s(-1)) and in a change of the power spectrum shape. Lower mean frequencies were observed at greater distances from the IZ independently of fatigue. The APB muscle seems to be fast fatigable and the relative decay rate of mean frequency was significantly larger than the one of force and MUCV.