OBJECTIVE: To explore clinical effect of iliac bone graft fixed with high strength suture arthroscopy in treating shoulder joint forward instability with high risk of dislocation. METHODS: The clinical data of 22 patients with shoulder forward instability with high risk of dislocation treated with iliac bone graft fixed with high-strength suture arthroscopy from January 2021 to January 2023 were retrospectively analyzed, including 14 males and 8 females, aged from 17 to 46 years old with an average of (26.50±8.26) years old;the times of dislocation ranged from 4 to 22 (11.08±5.82) times;7 patients on the left side and 15 patients on the right side. American Shoulder and Elbow Surgeons (ASES) score, University of California at Los Angeles (UCLA) score and Constant-Murley score were to evaluate the improvement of shoulder joint function before operation and 12 months after operation. Three-dimensional CT reconstruction was performed to evaluate the repair of glenoid bone defect, bone remodeling and bone healing before operation, immediately after and 12 months after operation. RESULTS: All patients were followed up for 12 to 24 months with an average of (18.68±3.92) months. No further dislocation or subluxation occurred in all patients. Scores of ASES, UCLA and Constant-Murley were improved from (69.50±2.26), (23.86±2.27), (75.64±3.58) before operation to (91.09±1.57), (32.27±2.03), (91.95±3.00) at 12 months after operation (P<0.05). The defect of glenoid bone was (12.41±7.55) %, (-37.23±3.75) %, (-22.41±3.58) % before opertaion, immediately and 12 months after operation, respectively, and the difference was statistically significant (P<0.05). Bone healing of iliac bone graft was achieved at 12 months after operation. CONCLUSION High strength suture arthroscopy to fix iliac bone graft for the treatment of shoulder forward instability with high dislocation risk is a safe and effective method, which could effectively restore shoulder stability and reduce surgical injury.
Humans ; Male ; Female ; Adult ; Arthroscopy/methods* ; Middle Aged ; Ilium/transplantation* ; Adolescent ; Joint Instability/physiopathology* ; Shoulder Dislocation/surgery* ; Shoulder Joint/physiopathology* ; Young Adult ; Retrospective Studies ; Bone Transplantation ; Sutures

PURPOSE: The purpose of this cadaveric study was to compare the volume and weight of bone graft harvested using the curettage vs. the trephination technique from the anterior iliac crest. METHODS: Embalmed cadavers were studied in this experimental research. The right hemipelvis of each cadaver was used for the trephine bone harvesting technique, whereas the left hemipelvis was used for the conventional curettage technique. The weight and the volume of the harvested bone were measured and statistically compared between the 2 sides. The Wilcoxon Signed-Rank test was employed to compare the graft volume and weight obtained from the right and left sides of the hemipelvis. RESULTS: Ten embalmed adult cadavers were used in this study. All subjects were Caucasian males with a mean age of 59.8 years (range 44 - 73 years) at the time of death. A total of 81 cylindrical bone grafts were harvested from the right iliac crest. In 9 out of 81 (11.1%), the cortex of the ilium was penetrated by the chisel. The mean weight of the bone graft harvested with the trephine technique (26.97 ± 2.32) g was heavier than that harvested with the curettage technique (23.74 ± 2.09) g (p = 0.007). Similarly, the volume of the bone graft was higher in the trephine technique (8.40 ± 0.84) cm³ compared to the curettage technique (6.60 ± 1.26) cm³ (p = 0.011). The trephination technique lasted a mean of (12.76 ± 1.87) min (range 10.30-16.10 min), while the curettage technique lasted a mean of (14.53 ± 0.89) min (range 13.50-16.00 min) (p = 0.028). CONCLUSION: Harvesting anterior iliac crest bone graft with the trephine technique provides a higher bone volume and weight than the conventional curettage technique. The trephine technique might be advocated over the curettage technique, especially when a large amount of autologous bone graft is required. However, a meticulous harvesting technique should be followed to prevent complications. In particular, the three-dimensional anatomy should be kept in mind, and the depth of trephination should be well-controlled. CLINICAL TRIAL REGISTRATION Institutional Review Board registration: 2022/499.
Humans ; Ilium/surgery* ; Male ; Middle Aged ; Aged ; Cadaver ; Curettage/methods* ; Tissue and Organ Harvesting/methods* ; Bone Transplantation/methods* ; Adult ; Trephining/methods*

OBJECTIVE: To investigate the short-term effectiveness of the anterior and middle columns in thoracolumbar tuberculosis reconstructed with whole autogenous spinous process-laminar bone through posterior approach. METHODS: The retrospective study included 78 patients with thoracolumbar tuberculosis who underwent posterior approach surgery and anterior and middle column bone graft reconstruction between January 2012 and May 2023. Based on the type of autogenous bone graft used, patients were divided into group A (whole autogenous spinous process-laminar bone graft, 38 cases) and group B (autogenous structural iliac bone graft, 40 cases). There was no significant difference of baseline data, such as age, gender, disease duration, involved segment of spinal tuberculosis, and preoperative erythrocyte sedimentation rate (ESR), C reactive protein (CRP), Oswestry disability index (ODI), visual analogue scale (VAS) score, the American Spinal Injury Association (ASIA) grade, segmental kyphotic angle, and intervertebral height between the two groups ( P>0.05). The operation time, intraoperative blood loss, postoperative drainage, hospital stays, ESR, CRP, VAS score, ODI, bone fusion time, ASIA grade for neurological status valuation, postoperative complications, change of segmental kyphotic angle, change of intervertebral height were recorded and compared between the two groups. RESULTS: The operation time in group A was significantly shorter than that in group B ( P<0.05); there was no significant difference in intraoperative blood loss, postoperative drainage, and hospital stays between the two groups ( P>0.05). All patients in the two groups were followed up 14-110 months (mean, 64.1 months); there was no significant difference in the follow-up time between the two groups ( P>0.05). The ESR, CRP, ODI, and VAS score at each time point after operation in both groups significantly improved when compared with those before operation, and further improved with the extension of time, the differences were significant ( P<0.05). There was no significant difference between the two groups ( P>0.05) except that the VAS score of group A was significantly better than that of group B at 3 days after operation ( P<0.05). There was no significant difference in fusion time between the two groups ( P>0.05). The neurological function of most patients improved after operation, and there was no significant difference in ASIA grade between the two groups at last follow-up ( P>0.05). There was no significant difference in segmental kyphosis angle and intervertebral height between the two groups at each time point ( P>0.05), and no significant difference in segmental kyphosis angle, intervertebral height correction and loss were found between the two groups ( P>0.05). In group A, there was 1 case of incision fat liquefaction and 1 case of incision infection; in group B, there was 1 case of deep venous thrombosis, 2 cases of pleural effusion, and 10 cases of pain in bone harvesting area; in both groups, there were 2 cases of gout caused by hyperuricemia. There was a significant difference in the incidence of pain in bone harvesting area between the two groups ( P<0.05), and there was no significant difference in the incidence of other complications between the two groups ( P>0.05). CONCLUSION Whole autogenous spinous process-laminar bone grafting is equivalent to structural iliac bone graft in reconstruction of the anterior and middle columns in thoracolumbar tuberculosis through posterior approach, effectively supporting the stability of the anterior and middle columns of the spine, while resulting in shorter operation time and less postoperative pain in bone harvesting area.
Humans ; Tuberculosis, Spinal/surgery* ; Thoracic Vertebrae/surgery* ; Lumbar Vertebrae/surgery* ; Bone Transplantation/methods* ; Retrospective Studies ; Male ; Female ; Treatment Outcome ; Plastic Surgery Procedures/methods* ; Adult ; Middle Aged ; Transplantation, Autologous ; Operative Time ; Ilium/transplantation*

OBJECTIVE: To investigate the biomechanical characteristics of Schatzker type Ⅱ tibial plateau fracture fixed by different bone grafting methods and internal fixations. METHODS: Twenty-four embalmed specimens of adult knee joint were selected to make Schatzker type Ⅱ tibial plateau fracture models, which were randomly divided into 8 groups (groups A1-D1 and groups A2-D2, n=3). After all the fracture models were restored, non-structural iliac crest bone grafts were implanted in group A1-D1, and structural iliac crest bone grafts in groups A2-D2. Following bone grafting, group A was fixed with a lateral golf locking plate, group B was fixed with lateral golf locking plate combined compression bolt, group C was fixed with lateral tibial "L"-shaped locking plate, and group D was fixed with lateral tibial "L"-shaped locking plate combined compression bolt. Compression and cyclic loading tests were performed on a biomechanical testing machine. A distal femur specimen or a 4-cm-diameter homemade bone cement ball were used as a pressure application mould for each group of models. The specimens were loaded with local compression at a rate of 10 N/s and the mechanical loads were recorded when the vertical displacement of the split bone block reached 2 mm. Then, compressive and cyclic loading tests were conducted on the fixed models of each group. The specimens were compression loaded to 100, 400, 700, and 1 000 N at a speed of 10 N/s to record the vertical displacement of the split bone block. The specimens were also subjected to cyclic loading at 5 Hz and 10 N/s within the ranges 100-300, 100-500, 100-700, and 100-1 000 N to record the vertical displacement of the split bone block at the end of the entire cyclic loading test. The specimens were subjected to cyclic loading tests and the vertical displacement of the split bone block was recorded at the end of the test. RESULTS: When the vertical displacement of the collapsed bone block reached 2 mm, the mechanical load of groups A2-D2 was significantly greater than that of groups A1-D1 ( P<0.05). The mechanical load of groups B and D was significantly greater than that of group A under the two bone grafting methods ( P<0.05); the local mechanical load of group D was significantly greater than that of groups B and C under the structural iliac crest bone grafts ( P<0.05). There was no significant difference ( P>0.05) in the vertical displacement of the split bone blocks between the two bone graft methods when the compressive load was 100, 400, 700 N and the cyclic load was 100-300, 100-500, 100-700 N in groups A-D. However, the vertical displacement of bone block in groups A1-D1 was significantly greater than that in groups A2-D2 ( P<0.05) when the compressive loading was 1 000 N and the cyclic load was 100-1 000 N. The vertical displacement of bone block in group B was significantly smaller than that in group A, and that in group D was significantly smaller than that in group C under the same way of bone graft ( P<0.05). CONCLUSION Compared with non-structural iliac crest bone grafts implantation, structural iliac crest bone grafts is more effective in preventing secondary collapse of Schatzker type Ⅱ tibial plateau fracture, and locking plate combined with compression bolt fixation can provide better articular surface support and resistance to axial compression, and the lateral tibial "L"-shaped locking plate can better highlight its advantages of "raft" fixation and show better mechanical stability.
Humans ; Bone Transplantation/methods* ; Tibial Fractures/physiopathology* ; Fracture Fixation, Internal/instrumentation* ; Biomechanical Phenomena ; Bone Plates ; Ilium/transplantation* ; Adult ; Tibia/surgery* ; Bone Cements ; Knee Joint/surgery* ; Male ; Tibial Plateau Fractures

OBJECTIVE: To evaluate the effectiveness of functional perforator flaps utilizing the superficial circumflex iliac artery as a vascular pedicle, as well as chimeric iliac bone flaps, in the reconstruction of composite tissue defects in the hand and foot. METHODS: A retrospective review of the clinical data from 13 patients suffering from severe hand or foot injuries, treated between May 2019 and January 2025, was conducted. The cohort comprised 8 males and 5 females, with ages ranging from 31 to 67 years (mean, 48.5 years). The injuries caused by mechanical crush incidents (n=9) and traffic accidents (n=4). The distribution of injury sites included 8 cases involving the hand and 5 cases involving the foot. Preoperatively, all patients exhibited bone defects ranging from 2.0 to 6.5 cm and soft tissue defects ranging from 10 to 210 cm². Reconstruction was performed using functional perforator flaps based on the superficial circumflex iliac artery and chimeric iliac bone flaps. The size of iliac bone flaps ranged from 2.5 cm×1.0 cm×1.0 cm to 7.0 cm×2.0 cm×1.5 cm, while the size of the soft tissue flaps ranged from 4 cm×3 cm to 15 cm×8 cm. In 1 case with a significant hand defect, a posterior interosseous artery perforator flap measuring 10.0 cm×4.5 cm was utilized as an adjunct. Likewise, an anterolateral thigh perforator flap measuring 25 cm×7 cm was combined in 1 case involving a foot defect. All donor sites were primarily closed. Postoperative flap survival was monitored, and bone healing was evaluated through imaging examination. Functional outcomes were assessed based on the location of the defects: for hand injuries, grip strength, pinch strength, and flap two-point discrimination were measured; for foot injuries, the American Orthopaedic Foot & Ankle Society (AOFAS) score, visual analogue scale (VAS) score, Maryland Foot Score, plantar pressure distribution and gait symmetry index (GSI) were evaluated. RESULTS: All flaps survived completely, with primary healing observed at both donor and recipient sites. All patients were followed up 6-18 months (mean, 12.2 months). No significant flap swelling or deformity was observed. Imaging examination showed a bone callus crossing rate of 92.3% (12/13) at 3 months after operation, and bone density recovered to more than 80% of the healthy side at 6 months. The time required for bone flap integration ranged from 2 to 6 months (mean, 3.2 months). One patient with a foot injury exhibited hypertrophic scarring at the donor site; however, no major complication, such as infection or bone nonunion, was noted. At 6 months after operation, grip strength in 8 patients involving the hand recovered to 75%-90% of the healthy side (mean, 83.2%), while pinch strength recovered to 70%-85% (mean, 80%). Flap two-point discrimination ranged from 8 to 12 mm, approaching the sensory capacity of the healthy side (5-8 mm). Among the 5 patients involving the foot, the AOFAS score at 8 months was 80.5±7.3, VAS score was 5.2±1.6. According to the Maryland Foot Score, 2 cases were rated as excellent and 3 as good. Gait analysis at 6 months after operation showed GSI above 90%, with plantar pressure distribution closely resembling that of the contralateral foot. CONCLUSION The use of functional perforator flaps based on the superficial circumflex iliac artery, combined with chimeric iliac bone flaps, provides a reliable vascular supply and effective functional restoration for the simultaneous repair of composite bone and soft tissue defects in the hand or foot. This technique represents a viable and effective reconstructive option for composite tissue defects in these anatomical regions.
Humans ; Male ; Middle Aged ; Female ; Perforator Flap/transplantation* ; Adult ; Plastic Surgery Procedures/methods* ; Hand Injuries/surgery* ; Aged ; Retrospective Studies ; Foot Injuries/surgery* ; Ilium/transplantation* ; Iliac Artery/surgery* ; Soft Tissue Injuries/surgery* ; Bone Transplantation/methods* ; Treatment Outcome

OBJECTIVE: To explore effectiveness of arthroscopic Eden-Hybinette procedure with Triple-Pulley and four point anti-rotation fixation technique in the treatment of recurrent anterior dislocation of shoulder joint. METHODS: A clinical data of 14 patients with recurrent anterior dislocation of shoulder joint and glenoid bone defect, who were met the selective criteria and admitted between February 2021 and February 2022, was retrospectively analyzed. All patients were treated with arthroscopic Eden-Hybinette procedure and the bone blocks were fixed by using Triple-Pulley and four point anti-rotation fixation technique. There were 9 males and 5 females with an average age of 31.2 years (range, 22-40 years). Shoulder dislocation occurred 4-10 times (mean, 6.8 times). The time from the initial dislocation to the admission was 1-6 years (mean, 3.3 years). The Instability Severity Index Score (ISIS) was 7.2±0.8, the Beighton score was 2.9±2.4, and the width ratio of glenoid bone defect was 26.64%±1.86%. Pre- and post-operative visual analogue scale (VAS) score, the University of Califonia-Los Angeles (UCLA) shoulder score, Constant score, and American Association of Shoulder and Elbow Surgeons (ASES) score were used to evaluate shoulder pain and function. The position, healing, resorption, and remodeling (glenoid area) of the bone blocks were evaluated by CT of shoulder joint. RESULTS: All patients underwent surgery successfully without any serious complications. All patients were followed up 11.5-13.8 months (mean, 12.0 months). The VAS scores of shoulder joint after operation decreased compared to preoperative levels, while the UCLA score, Constant score, and ASES score all increased, with significant differences ( P<0.05). And with the prolongation of time, the above indicators further improved, and the differences between different time points were significant ( P<0.05). Imaging reexamination showed that the bone block completely filled the glenoid defect, with good position and no significant displacement. Over time, the bone block healed and partially absorbed and remodelled. The postoperative glenoid area increased significantly compared to preoperative area ( P<0.05). With the prolongation of time, the glenoid area significantly decreased, but the difference was not significant between different time points ( P>0.05). CONCLUSION For the recurrent anterior dislocation of shoulder joint, Triple-Pulley and four point anti-rotation fixation technique in Eden-Hybinette procedure can effectively prevent bone rotation, make fixation more reliable, and easy to operate and achieve good effectiveness.
Humans ; Male ; Female ; Shoulder Dislocation/surgery* ; Adult ; Arthroscopy/methods* ; Ilium/transplantation* ; Bone Transplantation/methods* ; Shoulder Joint/surgery* ; Range of Motion, Articular ; Recurrence ; Treatment Outcome ; Joint Instability/etiology* ; Young Adult ; Transplantation, Autologous ; Rotation

OBJECTIVE: To conduct anatomical study on the iliac crest chimeric tissue flap and summarize its effectiveness of clinical application in repairing limb wounds. METHODS: Latex perfusion and anatomical study were performed on 6 fresh adult cadaver specimens with 12 sides, to observe the initial location, distribution, quantity, and direction of the common circumflexa iliac artery, the deep circumflexa iliac artery, and the superficial circumflexa iliac artery, and to measure their initial external diameter. Between December 2020 and September 2022, the iliac crest chimeric tissue flap repair was performed on 5 patients with soft tissue of limbs and bone defects. There were 3 males and 2 females, with an average age of 46 years (range, 23-60 years). Among them, there were 3 cases of radii and skin soft tissue defects and 2 cases of tibia and skin soft tissue defects. The length of bone defects was 4-8 cm and the area of skin soft tissue defects ranged from 9 cm×5 cm to 15 cm×6 cm. The length of the iliac flap was 4-8 cm and the area of skin flap ranged from 12.0 cm×5.5 cm to 16.0 cm×8.0 cm. The donor sites were directly sutured. RESULTS: Anatomical studies showed that there were 10 common circumflex iliac arteries in 5 specimens, which originated from the lateral or posterolateral side of the transition between the external iliac artery and the femoral artery, with a length of 1.2-1.6 cm and an initial external diameter of 0.8-1.4 mm. In 1 specimen without common circumflexa iliac artery, the superficial and deep circumflex iliac arteries originated from the external iliac artery and the femoral artery, respectively, while the rest originated from the common circumflex iliac artery. The length of superficial circumflex iliac artery was 4.6-6.7 cm, and the initial external diameter was 0.4-0.8 mm. There were 3-6 perforator vessels along the way. The length of deep circumflex iliac artery was 7.8-9.2 cm, and the initial external diameter was 0.5-0.7 mm. There were 3-5 muscular branches, 4-6 periosteal branches, and 2-3 musculocutaneous branches along the way. Based on the anatomical observation results, all iliac crest chimeric tissue flaps were successfully resected and survived after operation. The wounds at recipient and donor sites healed by first intention. All patients were followed up 8-24 months, with an average of 12 months. The tissue flap has good appearance and soft texture. X-ray film reexamination showed that all the osteotomy healed, and no obvious bone resorption was observed during follow-up. CONCLUSION The common circumflex iliac artery, deep circumflex iliac artery, and superficial circumflex iliac artery were anatomically constant, and it was safe and reliable to use iliac crest chimeric tissue flap in repairing the soft tissue and bone defects of limbs.
Adult ; Male ; Female ; Humans ; Middle Aged ; Plastic Surgery Procedures ; Ilium/surgery* ; Perforator Flap/blood supply* ; Skin Transplantation/methods* ; Lower Extremity/surgery* ; Soft Tissue Injuries/surgery* ; Treatment Outcome

Objective: To explore the clinical effects of proximal ulnar artery perforator flap combined with iliac bone graft in the reconstruction of subtotal thumb or finger defects. Methods: A retrospective observational study was conducted. From August 2016 to August 2019, 7 patients with thumb or finger defects caused by mechanical damage who met the inclusion criteria were admitted to Ruihua Affiliated Hospital of Soochow University, including 6 males and 1 female, aged 46 to 58 years. Their length of fingers was repaired with iliac bone, with length of 2.0 to 3.0 cm. After the bone graft, the skin defect area of the affected finger ranged from 2.8 cm×2.2 cm to 6.0 cm×3.2 cm. Then the free proximal ulnar artery perforator flap with area of 3.0 cm×2.4 cm to 6.5 cm×3.5 cm was used to cover the wounds. The wounds in donor sites of iliac crest and flap were directly sutured. The survival of flap in one week post surgery and the donor site wound healing in 2 weeks post surgery were observed, respectively. During the follow-up, the appearance and sensory function of the affected finger, bone healing, and scar hypertrophy of wound in the donor site were observed and evaluated. At the last follow-up, the functional recovery of the affected finger was evaluated with trial standard for the evaluation of functions of the upper limbs of the Hand Surgery Society of Chinese Medical Association. Results: In one week post surgery, all the flaps survived. In 2 weeks post surgery, the iliac bone and the wounds in forearm donor site healed. During the follow-up of 5 to 13 months, the flap was good in appearance, without obvious pigmentation; the sensory recovery reached level S₂ in 5 patients and S₀ in 2 patients; all the grafted iliac bones were bony union without obvious resorption; the wounds in donor site healed well, with only mild scar formation. At the last follow-up, the shape of the reconstructed finger was close to the healthy finger, and the functional evaluation results were excellent in 3 cases and good in 4 cases. Conclusions: The use of proximal ulnar artery perforator flap combined with iliac bone graft to reconstruct subtotal thumb or finger can partially restore part of the appearance and function, with less damage to the donor site. It is a good choice for patients who have low expectations of appearance and function for the reconstructed finger.
Male ; Humans ; Female ; Soft Tissue Injuries/surgery* ; Perforator Flap/transplantation* ; Skin Transplantation/methods* ; Thumb/surgery* ; Plastic Surgery Procedures ; Ulnar Artery/surgery* ; Cicatrix/surgery* ; Ilium/surgery* ; Treatment Outcome

Masquelet technique is one of the modalities for the treatment of long bone defect. Using cancellous bone graft to fill the bone defect is always a concern in children due to the small size of their iliac crest and open growth plate. We reported a case of 13-year-old male who presented with gap non-union of middle third of tibia. We applied a modified Masquelet technique by using only the cortical fibular graft instead of cancellous bone to fill the space surrounded by induced membrane. Fibula was used as a nonvascularized strut graft and matched stick graft to achieve complete union. We concluded that nonvascularized fibula grafting is an easy and effective option to fill the bone defect in children in the second stage of Masquelet technique.
Male ; Child ; Humans ; Adolescent ; Fracture Healing ; Bone Transplantation/methods* ; Fibula/transplantation* ; Tibia/surgery* ; Ilium/transplantation*

OBJECTIVE: To investigate the clinical results of locking compression plate combined with autologous iliac bone graft in the treatment of aseptic ulnar nonunion. METHODS: From March 2009 to July 2017, 22 patients with aseptic ulnar diaphyseal nonunion with complete follow-up data were treated with surgery, including 12 males and 10 females, aged from 16 to 58 (39.7±9.9) years old and ranging in course of disease from 10 to 192 (39.4±55.7) months. There were 15 atrophic nonunions, 5 hypertrophic nonunions and 2 synovial pseudo-articular nonunions. After debridement of the nonunion, locking compression plate was used to fix the nonunion and autogenous iliac bone graft was given. Bone healing rate, surgical complications and clinical results were evaluated. RESULTS: All the patients were followed up, and the duration ranged from 13 to 42 months, with a mean of (22.5±8.2) months, and 1 patient did not heal. Visual analogue pain scores ranged from 0 to 3 (0.9±0.9). Pronation of forearm was 47 to 86 (69.0±14.7) degrees, supination was 35 to 85 (63.0±9.4) degrees, wrist flexion was 20 to 80 (51.0±10.2) degrees, wrist flexion was 32 to 88 (71.0±11.7) degrees, elbow flexion contracture was 0 to 25 (9.0±5.6) degrees, further flexion was 105 to 150 (134.0±13.9) degrees, and grip strength was 87% on the opposite side. According to the Anderson scoring system, 8 cases were excellent, 11 were satisfied, 2 were not satisfied, and 1 was failed. CONCLUSIONS LCP combined with autologous iliac bone graft can effectively treat aseptic ulna diaphyseal nonunion.
Adolescent ; Adult ; Bone Plates ; Bone Transplantation ; Diaphyses ; Female ; Fracture Fixation, Internal ; Fractures, Ununited ; surgery ; Humans ; Ilium ; Male ; Middle Aged ; Retrospective Studies ; Treatment Outcome ; Ulna ; Young Adult