Stress distribution on the thorax after the Nuss procedure for pectus excavatum results in different patterns between adult and child patients

Presence of manubrium-sternum joint does not assure sufficient elevation of sternum in Nuss procedure for pectus excavatum patients

BACKGROUND

The manubrium and body of the sternum are connected by the manubrium-sternum joint (MSJ). In performing the Nuss procedure for pectus excavatum patients, the body of the sternum is elevated as the operator flips correction bars upside down. Theoretically, the presence of the MSJ should allow elevation of the sternum body. However, does the MSJ secure sufficient elevation of the sternum? This study aims to elucidate this clinical question.

METHODS

Seventy-four adult pectus excavatum patients with moderate to serious deformity (with Haller Index being equal to or greater than 5) were included in the study. The MSJ was open in all patients. For 29 patients, the sternum was elevated by only bar flipping (Non-Separation Group); for 45 patients, the sternum was horizontally separated after bar flipping (Separation Group). Whether or not additional elevation for Separation Group patients results from the division was observed, and the degree of the additional elevation was evaluated. Furthermore, 74 patients subjectively evaluated postoperative pain and gave scores with a Visual Analog Scale ranging from 0 (no pain) to 10 (intolerable pain). The VAS scores were compared between the two groups.

RESULTS

In the Separation Group, the sternums of all patients achieved additional elevation from sternum separation. The pain scores were lower for the Separation Group than for the Non-Separation Group.

CONCLUSION

Even when the MSJ is present, horizontal separation enhances the elevation of the sternum. Furthermore, horizontal separation of the sternum reduces postoperative pain.

Scapula alata, a rare complication after minimally invasive repair of pectus excavatum

A male patient in his early 30s underwent minimally invasive repair of pectus excavatum. According to standard Nuss bar procedure, a 30-degree thoracoscope was introduced through a right midaxillary 10 mm trocar in the 4th intercostal space. Two bars and five stabilisers were placed in a retromuscular position. After discharge, the patient experienced right upper back pain requiring prolonged opioid usage for three months and right scapular winging limiting functional activities. After conservative treatment with physiotherapy for 11 months, the patient still suffered from residual scapula alata with pain and muscle weakness. On suspicion of long thoracic nerve neuropraxia related to the thoracoscope placement, an electromyogram was conducted 16 months following surgery, revealing mild polyphasic potentials of the serratus anterior muscle without abnormal muscle unit action potential. After extended conservative therapy for another year, physical examination 28 months after surgery showed almost complete resolution of scapular winging.

Complication rates rise with age and Haller index in minimally invasive correction of pectus excavatum: A high-volume, single-center retrospective cohort study

OBJECTIVES

The study objectives were to describe the compounded complication rate of minimally invasive repair of pectus excavatum, identify predisposing risk factors, and evaluate the optimal timing of correction. Minimally invasive repair of pectus excavatum is the standard treatment for pectus excavatum and consists of 2 invasive procedures, for example, correction with bar insertion followed by bar removal after 2 to 3 years.

METHODS

A retrospective cohort study identifying children, adolescents, and adults of both genders corrected for pectus excavatum with minimally invasive repair of pectus excavatum between 2001 and 2022. Information on complications related to bar insertion and removal procedures for each individual patient was compiled into a compounded complication rate. Complication severities were categorized according to the Clavien-Dindo classification.

RESULTS

A total of 2013 patients were corrected by minimally invasive repair of pectus excavatum with a median age (interquartile range) for correction of 16.6 (5) years. Overall compounded complication rate occurred at a frequency of 16.4%, of which 9.3% required invasive reinterventions (Clavien-Dindo classification ≥IIIa). The complication rate related to bar insertion was 2.6-fold higher compared with bar removal (11.8% vs 4.5%, respectively). Multivariable analysis revealed age (adjusted odds ratio, 1.05; P < .001), precorrection Haller Index (adjusted odds ratio, 1.10; P < .033), and early-phase institutional experience (adjusted odds ratio, 1.59; P < .002) as independent predisposing risk factors. The optimal age of correction was 12 years, and the compounded complication rate correlated exponentially with age with a doubling time of 7.2 years. Complications increased 2.2-fold when the Haller index increased to 5 or more units.

CONCLUSIONS

Minimally invasive repair of pectus excavatum is associated with a high compounded complication rate that increases exponentially with age and high Haller Index. Consequently, we recommend repair during late childhood and early adolescence, and emphasize the importance of informing patients and relatives about the significant risks of adult correction as well as the need of 2 consecutive procedures taking the complication profile into account before planning surgery.

[Influencing factors on operating times for metal bar removal after Nuss repair]

BACKGROUND

Metal bar removal after the Nuss repair procedure is prone to be cancelled in cases of operating time shortages due it being suitable to be postponed without harming patients. Consequently, planning operation times as exactly as possible could be one solution.

OBJECTIVE

Statistical modelling of operation times of metal bar removal after Nuss repair using the prespecified independent predictors of age, sex, intraoperative complications, and number of implanted metal bars.

MATERIAL AND METHODS

We included all patients whose operation notes included an operation time, which was modelled via linear regression and subject to internal validation via bootstrap. Exploratory analyses also consisted of the surgeon's experience, the number of stabilizers, the body mass index, and preceding re-do surgery for bar dislocation.

RESULTS

We included 265 patients (14% ♀) with a median age of 19 years (interquartile range 17-20 years), of whom 81% had 1 and 17% had 2 metal bars removed. The prespecified regression model was statistically significant (likelihood ratio 56; df = 5; P < 0.001) and had a bias corrected R2 of 0.148. Patient age influenced operation times by 2.1min per year of life (95% confidence interval 1.3-2.9min; P < 0.001) and 16min per explanted metal bar (95% confidence interval: 10-22min; P < 0.001).

CONCLUSION

The patient-specific factors of age and the number of explanted metal bars influenced the operation times and can be included into scheduling operation times.

Modeling of the chest wall response to prolonged bracing in pectus carinatum

Pectus carinatum is a chest wall deformity that is often treated through the wearing of an external brace. The treatment of the deformity could benefit from a greater understanding of chest wall characteristics under prolonged loading. These characteristics are difficult to model directly but empirical studies can be used to create statistical models. 185 patients from 2018-2020 received bracing treatment. Data on the severity of the deformity, treatment pressures, and time of wear were recorded at the first fitting and all subsequent follow-up visits. This data was analyzed using a statistical mixed effects model to identify significant measures and trends in treatment. These models were designed to help quantify changes in chest wall characteristics through prolonged bracing. Two statistical models were created. The first model predicts the change in the amount of pressure to correct the deformity after bracing for a given time and pressure. The second model predicts the change in pressure response by the body on the brace after bracing for a given time and pressure. These models show a high significance in the amount of pressure and time to the changes in the chest wall response. Initial deformity severity is also significant in changes to the deformity. The statistical models predict general trends in pectus carinatum brace treatment and can assist in creating treatment plans, motivating patient compliance, and can inform the design of future treatment systems.

Pain Quality After Pediatric Pectus Excavatum Repair

BACKGROUND

Neuropathic pain medications are included in multimodal postoperative analgesic strategies, but quality of perioperative pain is rarely assessed.

AIMS

The purpose of this study was to describe adolescents' pain experiences after thoracoscopic pectus excavatum repair (Nuss procedure) using the Adolescent Pediatric Pain Tool.

DESIGN

This prospective descriptive longitudinal study was designed to test the hypothesis that pain quality descriptors reported are consistent with neuropathic pain.

METHODS

A convenience sample of 23 adolescents aged 12 to 17 years from a single urban, university affiliated, nonprofit children's hospital consented to self-report pain using the Adolescent Pediatric Pain Tool before and during hospitalization, and up to 14 months after Nuss procedure. Visual analytic techniques were used to analyze reported pain intensity, location, and affective, evaluative, sensory, and temporal qualities.

RESULTS

Postoperative pain quality, intensity, number of sites, and surface area decreased over time. Word clouds illustrated that neuropathic sensory and temporal pain quality descriptors increased in frequency 2 to 6 weeks after surgery and were the predominant descriptors 2 to 4 months after surgery. Dot matrix charts illustrated an inconsistent relationship of pain quality and intensity with pain surface area.

CONCLUSIONS

Pain quality should be assessed with valid, reliable, and developmentally appropriate tools. Visual analytics help illustrate pain quality at single points in time and longitudinally and may be helpful in guiding postoperative pain treatment.

Nuss Technique for Pectus Excavatum in Adult Patients: Cosmetic Satisfaction and Improvement of Quality of Life in a Single-Center Experience

Objectives

Since its introduction, the Nuss minimally invasive procedure for pectus excavatum (PE) repair (MIRPE) has become the method of choice. The current study describes our experience of PE correction in adults, with particular focus on postoperative outcomes, pain, quality of life, and patients’ satisfaction.

Methods

We enrolled for this observational study n = 93 adult patients from 2011 to 2018. The Haller index was used to quantify PE severity. Pulmonary function tests and cardiac examinations were performed preoperatively; we developed a standardized surgical technique and postoperative treatment, including follow-up at 3, 12, and 24 months after surgery and 6 months after bar removal. We also evaluated the quality of life and the satisfaction with the cosmetic result after the procedure with standardized questionnaires.

Results

No operative or perioperative deaths occurred nor life-treating complications. Thirteen complications occurred in 12 patients, with a total complication rate of 14% (n = 13/93). Pain intensity decreased in the follow-up [pain score visual analog scale at 3 months: median 1 (0–8); 12 months: median 1 (0–5); and 24 months: median 1 (0–4)]. Better or much better quality of life after the Nuss procedure was observed: n = 79 (84.1%) at 3 months, n = 80 (86%) at 12 months, and n = 85 (91.4%) at 24 months. After 2 years of observation, more than 90% of patients described improvement in their quality of life and satisfaction with the cosmetic results. Only a very small group of patients suffered from pain in the follow-up.

Conclusion

Our results demonstrate that the MIRPE procedure is safe and can be performed with excellent results in adults both for improvement of quality of life and for satisfaction with cosmetic results.

Stiffness reduction of the rib cage to perform a minimally invasive pectus excavatum repair: biomechanical evaluation

OBJECTIVES

To study the influence of sternal transection and costal chondrotomies on the stiffness and stresses in the rib cage of adult patients undergoing Nuss pectus excavatum procedure.

METHODS

Four pectus excavatum models with different Haller indexes were created by parameterizing a 3D model of a rib cage obtained based on a computed tomography scan of a patient with no pectus deformity. Using the finite element method, insertion of intrathoracic bars into all models was simulated in 3 conditions, namely, non-intervened, transverse sternal section and costal chondrotomies. Stiffness, stress distribution and maximum stresses for each case were obtained and compared.

RESULTS

Transverse sternotomy provided a reduction of 44% to 54% in the stiffness of the rib cage, depending on the Haller index analysed, while chondrotomies promoted a stiffness reduction of 70%. Stress distribution in the rib cage followed similar pattern for all the tested Haller index, but the maximum stress decreased by 36% when performing a transverse sternotomy, whereas when performing costal chondrotomies, it decreased by 47%.

CONCLUSIONS

Computational results report that transverse sternotomy reduces appreciably the stiffness of the rib cage, while costal chondrotomies promote even a higher stiffness reduction. Thus, these surgical procedures could improve the clinical outcomes of adult patients undergoing a pectus excavatum repair.

Nuss Procedure for Pectus Excavatum: A Comparison of Complications Between Young and Adult Patients

BACKGROUND

The Nuss procedure is the gold standard surgical treatment for pectus excavatum in young patients. Its use in adults has also been described, although it may be associated with increased postoperative morbidity resulting from higher chest wall rigidity. This study aimed to examine the risk of complications after the Nuss procedure in adult patients compared with young patients with pectus excavatum.

METHODS

This single-center retrospective cohort study evaluated all patients who underwent the Nuss procedure between 2006 and 2018. Patients were stratified by age as young (≤24 years old) and adult (>24 years old). The primary end point was the occurrence of perioperative or postoperative complications, subdivided into major (Clavien-Dindo class III_a or higher) and minor (less severe than Clavien-Dindo class III). Between-group differences were analyzed using the Mann-Whitney U and the χ² test with post hoc analysis.

RESULTS

A total of 327 participants were included, 272 in the young group (median age, 16 years; interquartile range [IQR], 15 to 18 years; range, 11 to 24 years) and 55 in the adult group (median age, 32 years; IQR, 27 to 38 years; range, 25 to 47 years). The median Haller index was similar between groups (young, 3.7; IQR, 3.2 to 4.4 vs adult,3.6; IQR, 3.0 to 4.3; P = .44). The median follow-up was 34 and 36 months, respectively. The incidence of major complications was comparable between young and adult participants (P = .43). Minor complications occurred more often among adults (young, 4% vs adult, 11%; P = .002). Chronic postoperative pain was the only minor complication with a significant difference in incidence (young, 1% vs adult, 7%; P = .008).

CONCLUSIONS

The Nuss procedure is a safe surgical treatment for pectus excavatum in both young and adult patients. The risk of major complications is comparable. However, adults more often have chronic pain.

The effect of minimally invasive pectus excavatum repair on thoracic scoliosis

OBJECTIVES

The Nuss technique comprises the placement of an intrathoracic bar behind the sternum. However, besides improving the body posture through the correction of the pectus excavatum (PE), this procedure may cause or worsen thoracic scoliosis as a result of the considerable stress loaded on the chest wall and the thorax. Our goal was to investigate the impact of the Nuss procedure on the thoracic spinal curvature in patients with PE.

METHODS

A total of 100 patients with PE who underwent the Nuss procedure were included in the study and evaluated retrospectively. The Haller index (HI), asymmetry index and sternal torsion angle were calculated from thoracic computed tomography images before the operation. To evaluate the scoliosis in the T2-T8 thoracic vertebrae, Cobb angles were calculated on a plain chest X-ray before the Nuss operation and after the removal of the bar. Cobb angles were classified as normal (5°), scoliotic posture (5°-10°) and scoliosis (>10°). All angles before and after the Nuss operation were compared. The patients were followed up for a mean of 41 months. Substernal bars were removed after a mean of 33 months.

RESULTS

The mean age of the patients was 19.6 ± 6.7 years. The Cobb angle was statistically significantly increased in all patients (P = 0.01), male patients (P = 0.01) and children (P = 0.046) but not in adults (P = 0.11) and female patients (P = 0.54). The Cobb angle was increased in patients with severe (HI ≥ 3.5) but not in patients with moderate (3.2 < HI < 3.5) or mild (2.0 < HI < 3.2) PE deformity.

CONCLUSIONS

The present study shows that the Cobb angle indicates that the severity of thoracic scoliosis increases following the Nuss procedure, particularly in male patients, in patients with mild and moderate sternal torsion angle and in those with a high preoperative HI. This alteration might be due to correctional forces and torque applied by the bar. Patients undergoing the Nuss procedure for the correction of PE should be followed up strictly for timely diagnosis and management of the scoliosis.

Bone-cartilage proportion in deformed ribs of male pectus excavatum patients

This study verifies the hypothesis that bone/cartilage proportion in deformed ribs of male pectus excavatum patients varies according to their ages. Anatomical evaluation of the thoraces was performed for 79 male pectus excavatum patients, referring to their three-dimensional computer-tomographic images. The patients were divided into Child Group (5-9 years old: n = 35); Adolescent Group (12-15 years old: n = 15) and Adult Group (18+ years old: n = 29). For each patient, the most concave point of the sternum was identified and the pair of ribs closest to the point were defined as Key Ribs. On each Key Rib, the most ventral point was defined as Prominent Point (PP); the junction between the bone and cartilage was defined as Costo-Chondral Junction (CCJ). The distances of these points from the spine were defined as Distance of Prominent Point (DPP) and Distance of Costo-Chondral Junction (DCCJ), respectively. The horizontal length of the Key Rib was defined as Rib Length (RL). Inter- and intra-group comparisons were performed for DPP/RL and DCCJ/RL. Inter-Group Comparison: DCCJ/RL is significantly smaller and DPP/RL is significantly greater in Adult Group than in Child Group, meaning CCJs shift medially and PPs shift laterally as patients get older. Intra-Group Comparison: In Child Group, DCCJ/RL is significantly greater than DPP/RL, meaning CCJs exist lateral to PPs. Contrarily, in Adult Group, DCCJ/RL is significantly smaller than DPP/RL, meaning CCJs exists medial to PPs. Bone/cartilage proportion in the concave part of the chest shifts according to patients' ages. To perform the Nuss procedure effectively, this age-related anatomical change must be taken into consideration.

Computer-Aided Design and Manufacturing Technology for Identification of Optimal Nuss Procedure and Fabrication of Patient-Specific Nuss Bar for Minimally Invasive Surgery of Pectus Excavatum

The Nuss procedure is one of the most widely used operation techniques for pectus excavatum (PE) patients. It attains the normal shape of the chest wall by lifting the patient’s chest wall with the Nuss bar. However, the Nuss bar is for the most part bent by a hand bender according to the patient’s chest wall, and this procedure causes various problems such as the failure of the operation and a decreased satisfaction of the surgeon and patient about the operation. To solve this problem, we proposed a method for deriving the optimal operation result by designing patient-specific Nuss bars through computer-aided design (CAD) and computer-aided manufacturing (CAM), and by performing auto bending based on the design. In other words, a three-dimensional chest wall model was generated using the computed tomography (CT) image of a pectus excavatum patient, and an operation scenario was selected considering the Nuss bar insertion point and the post-operative chest wall shape. Then, a design drawing of the Nuss bar that could produce the optimal operation result was derived from the operation scenario. Furthermore, after a computerized numerical control (CNC) bending machine for the Nuss bar bending was constructed, the Nuss bar prototype was manufactured based on the derived design drawing of the Nuss bar. The Nuss bar designed and manufactured with the proposed method has been found to improve the Haller index (HI) of the pectus excavatum patient by approximately 37% (3.14 before to 1.98 after operation). Moreover, the machining error in the manufacturing was within ±5% compared to the design drawing. The method proposed and verified in this study is expected to reduce the failure rate of the Nuss procedure and significantly improve the satisfaction of the surgeon and patient about the operation.

Separation patterns of orbital wall and risk of optic canal injury in Le Fort 3 osteotomy

PURPOSE

The authors hypothesized that the risks of optic canal injury in down-fracturing after Le Fort 3 osteotomy vary depending on the separation patterns of the orbital walls. This study verifies this hypothesis using biomechanical simulation.

METHODS

Ten finite-element skull models were produced using computer tomography data from ten persons. These models were modified to simulate Le Fort 3 osteotomy models by removing junctions between the neurocranium and facial cranium. The separation of the orbital wall was performed in four differing ways. In Type 1, all walls were completely separated. In Type 2, only the lateral wall was separated. In Type 3, the inferior wall was left unseparated. In Type 4, the lateral wall was left unseparated. Biomechanical simulation of down-fracturing was performed on the resulting 40 models. By observing irregular fractures occurring inside the orbit, the rate of optic canal involvement was evaluated for each of the four orbital-wall separation patterns.

RESULTS

The rates of optic canal involvement were: Type 1 (0/10), Type 2 (0/10), Type 3 (0/10), and Type 4 (4/10).

CONCLUSION

When the lateral wall is incompletely separated in Le Fort 3 osteotomy, irregular fracture can develop inside the orbit and involve the optic canal during the down-fracturing process. Hence, the lateral orbital wall should be completely separated to avoid potential blindness due to optic canal injury.

Comparison of Ultrasonography-guided Bilateral Intercostal Nerve Blocks and Conventional Patient-controlled Intravenous Analgesia for Pain Control After the Nuss Procedure in Children: A Prospective Randomized Study

Objectives:

Patients experience severe pain after pectus excavatum (PE) surgery. The aim of this prospective, randomized study was to compare analgesic effects of ultrasonography-guided bilateral intercostal nerve blocks (UG-ICNBs) with those of conventional patient-controlled intravenous analgesia (PCIA) on acute pain after the Nuss procedure for PE repair in children.

Methods:

A prospective randomized study was performed in children with PE who were scheduled for the Nuss procedure. Participants were randomly assigned to receive either UG-ICNBs or PCIA for postoperative analgesia. Faces Pain Scale-Revised scores, opioid consumption, analgesia-associated side effects (respiratory depression, pruritus, nausea, vomiting) during the first 24 hours, and lengths of stay in the postanesthesia care unit (PACU) and hospital were recorded after the surgery.

Results:

Sixty-two children undergoing the Nuss procedure were enrolled in the trial. Faces Pain Scale-Revised scores were significantly decreased in the UG-ICNBs group compared with the PCIA group for up to 6 hours after surgery. The opioid doses required in the PACU and during the first 24 hours after surgery were significantly greater in the PCIA group compared with the UG-ICNBs group. Accordingly, patients in the UG-ICNBs group showed a lower incidence of analgesia-associated side effects and faster PACU discharge compared with the PCIA group.

Conclusions:

Our study suggests that UG-ICNBs might be more effective than PCIA for postoperative analgesia in children who undergo the Nuss procedure for PE.

Subcutaneous local anesthetic infusion could eliminate use of epidural analgesia after the Nuss procedure

AIM

To compare outcomes of continuous subcutaneous infusion of local anesthetic and epidural analgesia following the Nuss procedure.

PATIENTS & METHODS

A retrospective chart review compared patients managed with subcutaneous local anesthetic infusion (n = 12) versus thoracic epidural (n = 19) following the Nuss procedure from March 2013 to June 2015.

RESULTS

There was no difference in hospital length of stay or days on intravenous narcotics. Epidural catheter placement prolonged operating room time (146.58 ± 28.30 vs 121.42 ± 21.98 min, p = 0.01). Average pain scores were slightly higher in the subcutaneous infusion group (3.72 ± 1.62 vs 2.35 ± 0.95, p = 0.02), but of negligible clinical significance.

CONCLUSION

Continuous subcutaneous infusion of local anesthetic could eliminate the need for thoracic epidural for pain management after the Nuss procedure.

Effects of Nuss procedure on thoracic scoliosis in patients with pectus excavatum

Background

The objectives of this study are to investigate the association between pectus excavatum (PE) and thoracic scoliosis (TS) and to analyze the effects of the Nuss procedure on the thoracic spinal curvature in patients with PE.

Methods

A total of 468 patients who underwent the Nuss procedure and pectus bar removal for PE from March 2011 to January 2015 were assessed and included into the present study.

Results

TS prevalence was 9.4% pre-correctively and 9.8% post-correctively. There was a positive correlation between age and Cobb angle (CA), pre-correctively and post-correctively (both, P<0.001). The late correction group (LG, age ≥10 years) had a higher CA and more frequent TS than the early correction group (EG, age <10 years) (pre-correction: CA 6.3±4.9° vs. 4.5±3.8°, P<0.001, TS P<0.001; post-correction: 7.6±7.2° vs. 4.1±3.3°, P<0.001, TS P<0.001). The post-corrective changes in CA were different according to the time of correction (decreased in EG: 4.5±3.8° vs. 4.1±3.3°, P=0.078; increased in LG: 6.3±4.9° vs. 7.6±7.2°, P=0.002). In patients with pre-corrective TS, CA after correction was decreased (post-correctively 11.9±10.0° vs. pre-correctively 13.9±6.0°, P=0.090). In addition, post-corrective CA was significantly decreased in EG (pre-correction 13.9±7.4° vs. post-correction 6.6±8.1°, P<0.001). However, post-corrective CA was increased in LG (pre-correction 13.8±4.5° vs. post-correction 16.7±9.2°, P=0.053). The number of patients with TS after correction was decreased in EG (P=0.194) and significantly increased in LG (P=0.028). There were both pre-corrective and post-corrective predictive factors for TS (Pre-corrective: age P<0.001, severity P=0.016, and BMI P=0.046; post-corrective: age at the time of correction P<0.001, weight P=0.046, and pre-corrective CA P<0.001).

Conclusions

The Nuss procedure had some significant effects on the thoracic spinal curvature, with early correction able to reduce TS in patients with PE.

[Differential approach for chest wall reconstruction for pectus excavatum in adults]

AIM

To perform the prospective non-randomized single-center trial of pectus excavatum correction in adults.

MATERIAL AND METHODS

For the period March 2012 - March 2016 64 patients aged 18-44 years were treated. Median age was 23 years. Male/female ratio was 41/23. All patients were included into standard survey protocol: chest MDCT, MRI of thoracic spine, pulmonary function test, echocardiography. Quality of life and complications rate after the Nuss procedure (n=50, 78.1%, group 1) and radical thoracoplasty using nikelid-titanium bar (n=14, group 2) were evaluated.

RESULTS

There was earlier recovery in the 1st group: 3 (2; 4) and 6 (5; 7) days after minimally invasive and radical thoracoplasty, respectively. Postoperative Dindo-Clavien I-IIIa complications developed in 46 (71.8%) patients. Most of them did not require additional procedures.

CONCLUSION

Nuss procedure is safe method and can be performed with good results in adults.

RESEARCH ON ELECTRICAL MEASUREMENT EXPERIMENT OF DEFORMATION OF ARTIFICIAL THORAX MODEL

The method of numerical simulation has been used in the research setting for purposes related to the correction process of the pectus excavatum with scoliosis. Although a convenient method, the validity and accuracy of this technique need to be tested. Further complicating the validity of this technique is that we are unable to confirm results of numerical simulation via electrical measurement experiments in humans because of ethical considerations, nor are we able to attain cadavers of pectus excavatum with scoliosis to perform electrical measurement experiments on. Both animal thorax and artificial thorax models can be used for thoracic deformation experiments, but the translation of these models to humans is unclear due to contrasting anatomical arrangements of chest cavities. This paper attempts to solve this problem by making a PVC thorax model and carrying out electrical measurement experiments to assess strain–displacement under physiological loading conditions. We present data showing biomechanical responses of the thoracic skeleton to compressive loading, which may be used to guide the development of computational models of the thoracic skeleton and ultimately improve the treatment strategy of pectus excavatum.

Minimally invasive repair of pectus excavatum (MIRPE) in adults: is it a proper choice?

INTRODUCTION

The Nuss procedure is suitable for prepubertal and early pubertal patients but can also be used in adult patients.

AIM

To determine whether the minimally invasive technique (MIRPE) can also be performed successfully in adults.

MATERIAL AND METHODS

Between July 2006 and January 2016, 836 patients (744 male, 92 female) underwent correction of pectus excavatum with the MIRPE technique at our institution. The mean age was 16.8 years (2-45 years). There were 236 adult patients (28.2%) (> 18 years) - 20 female, 216 male. The mean age among the adult patients was 23.2 years (18-45 years). The recorded data included length of hospital stay, postoperative complications, number of bars used, duration of the surgical procedure and signs of pneumothorax on the postoperative chest X-ray.

RESULTS

The MIRPE was performed in 236 adult patients. The average operative time was 44.4 min (25-90 min). The median postoperative stay was 4.92 ±2.81 days (3-21 days) in adults and 4.64 ±1.58 (2-13) in younger patients. The difference was not statistically significant (p = 0.637). Two or more bars were used in 36 (15.8%) adult patients and in 44 (7.5%) younger patients. The difference was not statistically significant either (p = 0.068). Regarding the overall complications, complication rates among the adult patients and younger patients were 26.2% and 11.8% respectively. The difference was statistically significant (p = 0.007).

CONCLUSIONS

MIRPE is a feasible procedure that produces good long-term results in the treatment of pectus excavatum in adults.

Contemporary management of recurrent pectus excavatum

BACKGROUND

Optimal management of recurrent pectus excavatum (PE) has not been established. Here, we review our institutional experience in managing recurrent PE to evaluate long-term outcomes and propose an anatomic classification of recurrences, and a decision-making algorithm.

METHODS

Clinical records of patients undergoing repair of recurrent PE (1996-2011) were reviewed. Univariate and multivariate logistic regression analyses were employed to examine patient characteristics as potential predictors for re-recurrence.

RESULTS

Eighty-five patients with recurrent PE were identified during the study period. The initial operation was a Ravitch procedure in 85% of cases. Revision procedures were most frequently Nuss repairs (N=73, 86%), with remaining cases managed via open approach. Overall cosmetic and functional results were satisfactory in 67 patients (91.8%) managed with Nuss and in 7 (58%) patients managed with other techniques. Seven (8%) patients required additional surgical revision. Multivariate analysis identified no statistically significant patient or procedural factors predictive of re-recurrence.

CONCLUSION

This study demonstrates that the Nuss procedure can be an effective intervention for recurrent pectus excavatum, regardless of the initial repair technique. However, open repair remains valuable when managing severe cases with abnormalities of the sternocostal junction and cartilage regrowth under the sternum.

A biomechanical study regarding the effect of tissue harvesting from the thorax on its movement during inspiration

OBJECTIVE

In the practice of plastic surgery, ribs and cartilage are often harvested for use in auto-grafts. This study aimed to elucidate the effect of such harvesting on the inspiration movement of the thorax.

MATERIALS AND METHODS

Sixteen three-dimensional computer simulation models were produced by reference to the CT data of 16 patients. To simulate the harvesting of ribs and costal cartilages, parts were removed from these thorax models, thereby producing models with different types of defect. By performing finite element calculation after applying contracture forces on the external intercostal muscles and diaphragm, the movement patterns exhibited by the thoraces during inspiration were analyzed. The relationships between the defect types and the movement patterns were evaluated with reference to the dynamic behavior of the sternum and the increase in thoracic volume.

RESULTS

Although the removal of costal cartilage can cause asymmetric movement of the thorax, it did not affect the inspiration movement of the thorax. However, removal of two or more ribs not only caused asymmetric movement of the thorax, but also negatively affected that movement. Removal of two or three ribs impaired the expansion of the hemi-thorax on inspiration by 10% and 40%, respectively.

CONCLUSION

The present study is the first to clarify the quantitative effect of tissue harvesting from the thorax on inspiration. The findings will be useful for surgeons when planning operations requiring harvesting of tissue from the thorax.

Chest-deformities: a proposal for a classification

BACKGROUND

In this article we assess the significance of classifying chest-deformities based on morphological findings in type-related treatment and its results.

DATA SOURCES

Recent publications on chest-deformities in children and youth were retrieved from PubMed and Medline and from our clinical and intraoperative findings.

RESULTS

Chest-deformities are diagnosed by thorax-measurements using a flexible meter projected on a graph-paper by MR/CT investigations and color coded videorasterstereography. In addition an ultrasound guided mediastinal analysis is performed on the heart, the great vessels and mediastinal organs. These investigations could determine meticulously the morphology of the sternum, the sterno-costal segments and the costal arch, enabling to find different chest wall deformities, i.e., 11 different types. The clinical and surgical significance of such a classification can be shown by comparing postoperative results of non-classified chest-deformities with those of classified. Preoperatively non-classified chest-deformities often have postoperative asymmetric shapes, partial local recurrences, costal arch eversions and a platythorax. Such a classification can be used to analyze and predict socalled "secondary associated alterations" of the vertebral column or mediastinal organs.

CONCLUSIONS

Determining the specific type of a thorax deformity could be considered a type-related physiotherapy as conservative treatment or vacuum treatment and if surgery is indicated a type-related surgical correction can be performed. A type-related and adapted surgical correction can prevent subsequent mitral valve prolapse, recurrent infections, vertebral disturbances caused by kypho-scoliosis and increasing psychological irritation. Typing chest-deformities are an additional and essential help for the surgeon to perform specific surgical procedures: detorsion of the sternum, correction of the sterno-costal region, the costal arch bow and the kind of chest wall immobilization by metal struts. It can also compare the postoperative results more accurately in similar types of chest-deformities.

Dynamic effects of the Nuss procedure on the spine in asymmetric pectus excavatum

OBJECTIVE

This study aimed to elucidate dynamic effects of the Nuss procedure on the spine in the treatment of patients with pectus excavatum with asymmetric thoraces.

METHODS

Twenty-five patients with pectus excavatum who underwent the Nuss procedure were categorized into 4 groups by preoperative morphology of the spine and thoracic asymmetry. In group 1 (n = 8), the right side of the thorax was concave and the spine bowed to the right. In group 2 (n = 4), the right side of the thorax was concave and the spine bowed to the left. In group 3 (n = 5), the left side of the thorax was concave and the spine bowed to the right. In group 4 (n = 8), the left side of the thorax was concave and the spine bowed to the left. With computed tomographic data, finite-element models were produced to simulate each patient's thorax. Thereafter, dynamic response patterns of the spine to the Nuss procedure were examined. Validity of these biomechanical findings was verified by referring to clinical outcomes.

RESULTS

In group 1 and group 4 models, deformed spines were straightened; in group 2 and group 3 models, spinal bowing increased. These biomechanical findings were compatible with clinical evaluations.

CONCLUSIONS

Performance of the Nuss procedure for asymmetric pectus excavatum exerts dynamic influence on the spine. Response patterns of the spine are predictable from morphologic relationships between the asymmetric patterns of the anterior thoracic wall and the spine.

Anatomical, histologic, and genetic characteristics of congenital chest wall deformities

There is a large and diverse group of congenital abnormalities of the thorax that manifest as deformities and/or defects of the anterior chest wall and, depending on the severity and concomitant anomalies, may have cardiopulmonary implications. Pectus excavatum, the most common anterior chest deformity, is characterized by sternal depression with corresponding leftward displacement and rotation of the heart. Pectus carinatum, the second most common, exhibits a variety of chest wall protrusions and very diverse clinical manifestations. The cause of these conditions is thought to be abnormal elongation of the costal cartilages. Collagen, as a major structural component of rib cartilage, is implicated by genetic and histologic analysis. Poland syndrome is a unique unilateral chest/hand deficiency that may include rib defects, pectoral muscle deficit, and syndactyly. Cleft sternum is a rare congenital defect resulting from nonfusion of the sternal halves, which leaves the heart unprotected and requires early surgical intervention.

Routine use of minimally invasive surgery for pectus excavatum in adults

BACKGROUND

The Nuss operation, a minimally invasive repair of pectus excavatum, is considered the treatment of choice in children. It is controversial in adults, but smaller series have been published. We have used the Nuss operation routinely in adults since 2003.

METHODS

The indication for operation was a patient-described disabling cosmetic appearance. We modified the operation by using a shorter pectus bar, which appears to be more stable. All patient records were available and analyzed retrospectively.

RESULTS

Operations for pectus excavatum were done in 475 patients (89% men) at Aarhus University Hospital. 180 patients (38%) were aged 18 years or older, median patient age was 22 years (range, 18 to 43 years). All but one patient achieved an excellent cosmetic result. Two pectus bars were required in 57 patients (32%), and 2 patients required 3 pectus bars. The median duration of the procedure was 41 minutes (range, 16 to 119 minutes), which was significantly longer compared with younger patients, but the difference was not clinically relevant (6 minutes). Pneumothorax occurred in 86 patients (48%), but only 4 (2%) required chest tube drainage. In 3 patients the pectus bar dislocated during follow-up.

CONCLUSIONS

Minimally invasive repair for pectus excavatum can be performed safely in adults, with excellent immediate cosmetic results. Adults often require more than 1 pectus bar. From the results of this large series, we conclude that patients aged younger than 50 years are eligible for minimally invasive surgical correction of pectus excavatum.