The Synovium of Human Osteoarthritic Joints Retains Its Chondrogenic Potential Irrespective of Age.

The autologous synovium is a potential tissue source for local induction of chondrogenesis by tissue engineering approaches to repair articular cartilage defects that occur in osteoarthritis. It was the aim of the present study to ascertain whether the aging of human osteoarthritic patients compromises the chondrogenic potential of their knee-joint synovium and the structural and metabolic stability of the transformed tissue. The patients were allocated to one of the following two age categories: 54-65 years and 66-86 years (n = 7-11 donors per time point and experimental group; total number of donors: 64). Synovial biopsies were induced in vitro to undergo chondrogenesis by exposure to bone morphogenetic protein-2 (BMP-2) alone, transforming growth factor-ß1 (TGF-ß1) alone, or a combination of the two growth factors, for up to 6 weeks. The differentiated explants were evaluated morphologically and morphometrically for the volume fraction of metachromasia (sulfated proteoglycans), immunohistochemically for type-II collagen, and for the gene expression levels of anabolic chondrogenic markers as well as catabolic factors by a real-time polymerase chain reaction analysis. Quantitative metachromasia revealed that chondrogenic differentiation of human synovial explants was induced to the greatest degree by either BMP-2 alone or the BMP-2/TGF-ß1 combination, that is, to a comparable level with each of the two stimulation protocols and within both age categories. The BMP-2/TGF-ß1combination protocol resulted in chondrocytes of a physiological size for normal human articular cartilage, unlike the BMP-2-alone stimulation that resulted in cell sizes of terminal hypertrophy. The stable gene expression levels of the anabolic chondrogenic markers confirmed the superiority of these two stimulation protocols and demonstrated the hyaline-like qualities of the generated cartilage matrix. The gene expression levels of the catabolic markers remained extremely low. The data also confirmed the usefulness of experimental in vitro studies with bovine synovial tissue as a paradigm for human synovial investigations. Our data reveal the chondrogenic potential of the human knee-joint synovium of osteoarthritic patients to be uncompromised by aging and catabolic processes. The potential of synovium-based clinical engineering (repair) of cartilage tissue using autologous synovium may thus not be reduced by the age of the human patient. Impact statement Our data reveal that in younger and older age groups alike, synovial explants from osteoarthritic joints can be equally well induced to undergo chondrogenesis in vitro; that is, the chondrogenic potential of the human synovium is not compromised by aging. These findings imply that the autologous synovium represents an adequate tissue source for the repair of articular cartilage in clinical practice by tissue engineering approaches in human patients suffering from osteoarthritis, independent of the patient's age.

Functional and magnetic resonance imaging outcome after polyurethane meniscal scaffold implantation following partial meniscectomy.

PURPOSE: Prevention of the knee osteoarthritis following meniscectomy is implantation of an allotransplant or an artificial meniscus. We present retrospective study of our early results of the treatment using polyurethane meniscal scaffold. METHODS: From 2016 to 2020, we implanted nine polyurethane scaffolds (Actifit) after partial meniscectomy, five males and four females, age 36 (16-47), BMI 26.7 (17.2-35.9) kg/m2. Functional status, activity, pain, and MRI were assessed. RESULTS: FU 20.8 (6-48.5) months, 35.2 (0-68) months from the meniscectomy to the implantation. The average implant length was 46.1 (35-60) mm, average number of sutures was 7.6 (5-10). Lysholm score before surgery was 61.7 (49-85), after the surgery 86.4 (62-95) with p 0.0045, Tegner activity score before meniscectomy was 5.8 (4-7), after 3.8 (2-5), and after the scaffold implantation 4.6 (3-7) with p 0.0488. Before surgery, VAS score was 3.1 (2-4), and after 7.7 (5-9) with p 0.0042. Pursuant to the Genovese classification, the last follow-up MRI showed a type 2 meniscal morphology in four cases and a type 3 in five cases. Seven patients had type 1 and two had type 2 signal intensity. On average, the absolute extrusion of a transplanted meniscus was 3.67 mm, and the relative extrusion was 0.58 mm. Extrusion progress was not detected. CONCLUSION: Significantly improved knee functionality, increased level of physical activity, and reduced pain. MRI analysis revealed the meniscal transplant morphology and volume loss, as well as its extrusion without progression.

Correction to: Intraarticular application of autologous conditioned serum (ACS) reduces bone tunnel widening after ACL reconstructive surgery in a randomized controlled trial.

The Orthokine product used in the trial was donated by the manufacturer.

Influence of tranexamic acid on postoperative autologous blood retransfusion in primary total hip and knee arthroplasty: a randomized controlled trial.

BACKGROUND: Postoperatively shed blood salvage is commonly used to reduce allogenic blood transfusion in patients undergoing total hip (THA) and knee arthroplasty (TKA). Autologous blood retransfusion is not devoid of risk. We hypothesized that adding tranexamic acid (TXA) to a restrictive blood transfusion protocol would reduce the need for postoperative autologous blood retransfusion in primary knee and hip arthroplasty. STUDY DESIGN AND METHODS: Ninety-eight adult patients undergoing primary THA or TKA were randomly assigned to receive an intraoperative intravenous loading dose of 1.0 g of TXA followed by another 1.0-g dose 3 hours later (TXA group) or a matching volume 0.9% saline placebo (control group). A postoperatively shed autologous blood recovery system was used in all patients and the minimum reinfusion volume set at 250 mL. Red blood cells were transfused if hemoglobin level was less than 8 or if 8 to 10 g/dL with symptoms of anemia. RESULTS: The proportion of patients receiving autologous blood reinfusion was significantly lower in the TXA group (5/49) compared to placebo (42/49) with an absolute difference of -75.5% (adjusted relative risk, 0.005), and none of the patients in the TXA group received more than 400 mL retransfused. Median total external blood loss during the first 24 hours was lower in the TXA group, 320 mL (range, 80-930 mL), compared to 970 mL (range, 100-2600 mL) in the placebo group (p < 0.001). There were no significant differences in homologous blood transfusions and hematologic variables between groups. Treatment differences were consistent by size and significance when the analysis was repeated separately in patients undergoing TKA or THA. CONCLUSION: Addition of TXA to a restrictive transfusion protocol makes the use of a postoperative blood salvage system in patients undergoing primary hip and knee arthroplasty unnecessary.

Arthroscopic decompression of suprapatellar cyst: case report.

Bursae around the knee reduce friction between moving structures. When involution of suprapatellar septum fails to occur ("complete septum"), then suprapatellar bursa may stay completely separated from the knee joint cavity to form a cystic cavity. In the case of the increased volume, suprapatellar bursitis can cause painful suprapatellar swelling. The aim is to point to the possibility of arthroscopic decompression of suprapatellar cyst. In the case presented, the indication for knee arthroscopy was based on clinical examination, ultrasonography and magnetic resonance studies. The preoperative diagnosis was verified intra-operatively, and intra-articular cyst decompression was performed by arthroscopy. At the final examination 8 months postoperatively, the patient still had no pain, swelling and had full range of motion. This minimally invasive operative procedure resulted in a satisfactory anatomic and functional outcome. In this case report, we present a patient with suprapatellar cyst submitted to arthroscopic cyst decompression.

Endoscopic treatment of the external snapping hip syndrome: surgical technique and report of two cases.

Snapping hip or coxa saltans is a condition characterized by an audible and/or palpable snapping during hip movement and can be associated with pain around the hip. There are various causes of this condition and can be divided into two types: extra-articular and intra-articular. The most common type is the external extra-articular, where the snapping is due to thickened posterior part of the iliotibial band or anterior part of the gluteus maximus muscle sliding over the greater trochanter during hip movement. Two patients with external snapping hip are presented, who were treated with our original endoscopic iliotibial band release and greater trochanteric bursectomy. There were no surgical complications and the patients did not experience snapping or pain in the hip during 24-month follow-up period. Results of various open techniques and one endoscopic technique in the treatment of external snapping hip are also reported.

[Osteochondral fracture of the patella after acute dislocation]. / Kostano-hrskavicni prijelom ivera kao posljedica akutne luksacije.

Acute patellar dislocation is a common injury in young athletes, which occurs due to inappropriate biomechanical relations and anatomic deviations in the area of knee joint. In these unfavorable conditions, abrupt and vigorous strain of the quadriceps muscle of the thigh may result in lateral patellar dislocation. A case is presented of a young male athlete with acute patellar dislocation and consequential osteochondral fracture. Although x-ray showed normal knee finding, typical history, clinical examination and magnetic resonance image of the knee indicated arthroscopy, which confirmed the diagnosis ofpatellar dislocation. The osteochondral fragment was found and fastened by screws, thus reconstructing the articular surface of the patella. Medial patellar stabilizers were strengthened and lateral stabilizers loosened, thus re-establishing its anatomic slide way. On second-look operation, the screws were removed. In this case, good anatomic and functional outcome was achieved by timely operative treatment, joint surface reconstruction and rehabilitation.

Value of ß2-microglobulin in the serum of healthy subjects older than 40 years.

The aim of this research was to determine if the age of healthy subjects older than 40 years of age has an influence on the concentration of ß(2) -microglobulin in the serum of subjects of different populations. We examined the values of ß(2) -microglobulin in the serum of 51 healthy subjects aged 40-86 years using the microparticle enzyme immunoassay AxSYM ß(2) -microglobulin test. The reference values of ß(2) -microglobulin according to the nonparametric statistical method is 0.95-2.73 mg/L. A correlation was found between ß(2) -microglobulin and age: 40-50 years (0.94-1.54 mg/L), 51-65 years (0.96-2.62 mg/L), and >65 years (1.13-2.84 mg/L). There was no significant statistical difference of ß(2) -microglobulin between genders (P > 0.05); however, there was a statistically significant difference between the concentration of ß(2) -microglobulin and the subjects' age. (Spearman's rank correlation coefficient ρ = 0.66; P < 0.01). A direct correlation between age and the concentration of ß(2) -microglobulin was observed. This research is a contribution to determining reference values of ß(2) -microglobulin in subjects of different populations.

Intraarticular application of autologous conditioned serum (ACS) reduces bone tunnel widening after ACL reconstructive surgery in a randomized controlled trial.

PURPOSE: Pro-inflammatory cytokines play a pivotal role in osteoarthritis, as well as in bone tunnel widening after ACL reconstructive surgery. A new treatment option is to administer autologous conditioned serum (ACS) containing endogenous anti-inflammatory cytokines including IL-1Ra and growth factors (IGF-1, PDGF, and TGF-ß1, among others) in the liquid blood phase. The purpose of this trial was to establish whether the postoperative outcome could be affected by intraarticular application of ACS. METHODS: In a prospective, randomized, double-blinded, placebo-controlled trial with two parallel groups, 62 patients were treated. Bone tunnel width was measured by CT scans, while clinical efficacy was assessed by patient-administered outcome instruments (WOMAC, IKDC 2000) up to 1 year following the ACL reconstruction in patients receiving either ACS (Group A) or placebo (Group B). We compared the levels and dynamics of IL-1ß concentrations in the synovial liquid and examined the correlation between the levels of IL-1ß at three different postoperative points. RESULTS: Bone tunnel enlargement was significantly less (6 months: 8%, 12 months: 13%) in Group A than in Group B (6 months: 31%, 12 months: 38%). Clinical outcomes (WOMAC, IKDC 2000) were consistently better in patients treated with ACS at all data points and for all outcome parameters, and there were statistically significant differences in the WOMAC stiffness subscale after 1 year. The decrease in IL-1ß synovial fluid concentration was more pronounced in the ACS group, and values were lower, to a statistically significant degree, in the ACS group at day 10. CONCLUSION: The intraarticular administration/injection of ACS results in decreased bone tunnel widening after ACL reconstructive surgery.

Correlation between synovial fluid and serum IL-1beta levels after ACL surgery-preliminary report.

The possibility of controlling the harmful intra-articular influence of elevated interleukin (IL)-1beta synovial fluid concentration after anterior cruciate ligament (ACL) surgery could be useful. We investigated the correlation between serum and synovial fluid IL-1beta levels following ACL reconstruction. We measured IL-1beta concentration periodically in three synovial fluid and four serum samples in each of 20 patients receiving either autologous conditioned serum (ACS) containing endogenous anti-inflammatory cytokines including IL-1Ra and several growth factors (group A) or placebo (group B). A decrease in IL-1beta synovial fluid concentration appeared to be more pronounced in absolute terms in group A. In eight patients serum IL-1beta was detected on the 6th postoperative day. In four of them whose synovial fluid levels were over 10 pg/ml on the 6th postoperative day, serum IL-1beta was detected on the 10th postoperative day. The results were different in group B. Correlation between serum and synovial fluid IL-1beta appearance persists in patients after ACL surgery and ACS application. This study is an example of ACS influence on the ACL healing process controlling the IL-1beta levels on the basis of the serum IL-1beta detection.

Characterized chondrocyte implantation results in better structural repair when treating symptomatic cartilage defects of the knee in a randomized controlled trial versus microfracture.

BACKGROUND: As the natural healing capacity of damaged articular cartilage is poor, joint surface injuries are a prime target for regenerative medicine. Characterized chondrocyte implantation uses an autologous cartilage cell therapy product that has been optimized for its biological potency to form stable cartilage tissue in vivo. PURPOSE: To determine whether, in symptomatic cartilage defects of the femoral condyle, structural regeneration with characterized chondrocyte implantation is superior to repair with microfracture. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: Characterized chondrocyte implantation was compared with microfracture in patients with single grade III to IV symptomatic cartilage defects of the femoral condyles in a multicenter trial. Patients aged 18 to 50 years were randomized to characterized chondrocyte implantation (n = 57) or microfracture (n = 61). Structural repair was blindly assessed in biopsy specimens taken at 1 year using (1) computerized histomorphometry and (2) evaluation of overall histological components of structural repair. Clinical outcome was measured using the self administered Knee injury and Osteoarthritis Outcome Score. Adverse events were recorded throughout the study. RESULTS: Characterized chondrocyte implantation resulted in better structural repair, as assessed by histomorphometry (P = .003) and overall histologic evaluation (P = .012). Aspects of structural repair relating to chondrocyte phenotype and tissue structure were superior with characterized chondrocyte implantation. Clinical outcome as measured by the Knee injury and Osteoarthritis Outcome Score at 12 to 18 months after characterized chondrocyte implantation was comparable with microfracture at this stage. Both treatment groups had a similar mean baseline overall Knee injury and Osteoarthritis Outcome Score (56.30 +/- 13.61 and 59.53 +/- 14.95 for microfracture and characterized chondrocyte implantation, respectively), which increased in both groups to 70.56 +/- 12.39 and 72.63 +/- 15.55 at 6 months, 73.26 +/- 14.66 and 73.10 +/- 16.01 at 12 months, and 74.73 +/- 17.01 and 75.04 +/- 14.50 at 18 months, respectively. Both techniques were generally well tolerated; the incidence of adverse events after characterized chondrocyte implantation was not markedly increased compared with that for microfracture. CONCLUSION: One year after treatment, characterized chondrocyte implantation was associated with a tissue regenerate that was superior to that after microfracture. Short-term clinical outcome was similar for both treatments. The superior structural outcome may result in improved long-term clinical benefit with characterized chondrocyte implantation. Long-term follow-up is needed to confirm these findings.

Regeneration of the skeleton by recombinant human bone morphogenetic proteins.

Recombinant human bone morphogenetic proteins (rhBMPs) have past a long journey in human orthopaedic surgery during the last 15 years. From the first reports of the use of rhBMPs in hostile environments such as critically-sized bone defects, avascular femoral head necrosis, unstable thoracolumbar vertebral fractures, instability between the atlas and axis due to rheumatoid arthritis; over the use for nonunions of long bones and the scaphoid, reconstructive and revision surgeries of the hip, acute fractures, allograft nonunions, congenital pseudarthrosis, and various approaches of lumbar and cervical spine fusions, rhBMPs overgrow to a safe and reliable device in the treatment of open tibial shaft fractures, nonunions of long bone fractures, anterior lumbar interbody fusion and revision posterolateral lumbar fusions. Systematic review of the published literature of rhBMPs is presented.

[Cultivation and implantation of chondrocytes]. / Uzgoj i primjena hrskavicnih stanica.

Autologous chondrocyte transplantation is applied in patients with symptomatic articular cartilage defect due to a prior unsuccessful procedure on damaged cartilage, with a purpose to regenerate the cartilage. The procedure starts with an orthopedic surgeon establishing chondral defect in a joint and, during the knee arthroscopy, referring to the laboratory a cartilage biopsy specimen of a rice size from a non-weight-bearing part of the joint (usually the lateral part of the knee trochlea). Qualified biologists and technicians at the laboratory will then separate the cartilage cells from the extracellular matrix, followed by storing parts of healthy cartilage (300-500 mg) into a medium containing antibiotics, antimycotics and ascorbic acid, Individual cartilage cells (chondrocytes) will be isolated by enzymatic digestion. Chondrocytes are finally grown in sterile conditions in the patient's autologous serum during the next 14-21 days. During that time, the culture medium is tested several times in the micro laboratory and the cells' chondrogenic phenotype is determined. Multiplied chondrocytes are then removed from the bottom of the dish, washed several times, counted and prepared in a low volume medium (50-100 microL) suitable for implantation into the injured joint. During the surgery, orthopedic surgeon injects the cell implant under the periosteum or a similar biological membrane covering the defect. Active joint movement starts after 2-3 days, and full weight bearing is achieved in the next several weeks, following the rehabilitation protocol. Full physical condition is achieved within one year. Autologous chondrocyte transplantation is used for treatment of focal articular cartilage defects in the early stages of the disease, thus preventing or delaying progression to osteoarthritis and, consequently, replacement of the joint by an endoprosthesis.

Plasma cytokines as markers of aseptic prosthesis loosening.

The proinflammatory cytokines IL-1beta, IL-8, and TNF-alpha play a major role in the process of bone resorption during aseptic loosening of large joint prostheses. These cytokines secreted locally during bone resorption in aseptic loosening may enter peripheral circulation. Increased concentration of IL-1gamma, IL-8, and TNF-alpha in peripheral circulation may indicate aseptic loosening. We determined whether bone resorption could be verified by cytokine presence in plasma. We recruited 50 patients with aseptic prosthesis loosening, 50 with stable prostheses, 50 with osteoarthritis, and 50 healthy individuals. Cytokine levels were determined in plasma by ELISA tests. Patients with prosthesis loosening had higher plasma levels (IL-10, 3.7 +/- 5.5 pg/mL; IL-8, 14.7 +/- 9 pg/mL; TNF-alpha, 32.7 +/-+/- 32.4 pg/mL) than patients with stable prostheses (IL-1beta, 1.5 +/- 2 pg/mL; IL-8, 8.1 +/- 4.7 pg/mL; TNF-alpha, 22.9 +/- 18.7 pg/mL), patients with osteoarthritis (IL-1beta, 0.7 +/- 1.1 pg/mL; IL-8, 5.8 +/- 3.8 pg/mL; TNF-alpha, 9.8 +/- 7.7 pg/mL) and healthy individuals (IL-1beta, 0.7 +/- 1.1 pg/mL; IL-8, 4.2 +/- 1.3 pg/mL; TNF-alpha, 3.9 +/- 3.9 pg/mL). Our data suggest elevated plasma levels of proinflammatory cytokines may be useful as markers of bone resorption in the laboratory diagnosis of prosthesis loosening.

[Surgical treatment of the knee osteoarthritis]. / Kirursko lijecenje osteoartritisa kouena.

Surgical treatment of initial osteoarthritis consists of palliative arthroscopic operation, joint toilet, arthroscopic lavage, chondrectomy, meniscectomy, sinovyectomy, meniscus toilet, abrasion arthroplasty, microfracture, mosaicplasty, transplantation of autologic chondrocytes. To cure deviation of axis it is proposed corrective osteotomy in pre-osteoarthritis phase. Partial or total arthroplasty is recommended in treatment of advanced knee degenerative process.

[Unicondylar knee arthroplasty with "Repicci" model]. / Artroplastika koljenskog zgloba monokondilarnom endoprotezom model "Repicci".

Development of mini invasive techniques for implantation of unicondylar knee prostheses has increased general interest in this type of surgery. Indications are single compartment arthrosis, patients over 50 years of age with total body weight of less then 80 kg with small axis deviations and ligaments preserved. Important contraindications are systemic diseases. Authors present mid-term postoperative results for 25 patients and 26 knees after implantation of unicondylar knee prosthesis type Repicci. Average age at time of surgery was 64.3, predominantly women and in all patients varus deformity with medial compartment arthrosis was seen. According to the Ahlback classification patients were from type 1 to type 4. Average follow up was 31.8 months. We achieved good axial correction with femorotibial angle of 6.2 degrees postoperatively, with flexion of 118 degrees and only in 3 knees extension lag was seen of an average of 8.3 degrees. According to the Knee Society Questionnaire, knee score was 60 points preoperatively and 86.8 points postoperatively and functional score was 30.9 points preoperatively and 71.1 points postoperatively. Pain level, according to the Visual Analogue Scale, was preoperatively 6.8 points and 2 points postoperatively (10 was max). We conclude that the unicondylar knee arthroplasty is a good solution for patients with early degenerative changes in one knee compartment. This type of operative procedure will be more used because of numerous advantages when compared to other treatment options.

[Emergencies in the knee joint surgery]. / Hitna stanja u ortopediji u podrucju koljenskog zgloba.

Anatomy of the knee joint is one of the most complicated when compared to other joints in the human body. Due to high demands and strong forces acting on the knee joint, it is also one of the most injured joints. Every structure in the joint can be damaged and some of the damages demand earlier treatment. Except intraarticular fractures, stress fractures of the proximal tibia, as a result of lower extremity malalignment, need earlier treatment to prevent the dislocation of the fragments. Damage to the articular cartilage needs earlier treatment due to its tendency to involve wider area of the joint. Meniscus rupture is not an indication for earlier treatment, except a "bucket handle" rupture due to its potential to block the movements of the knee joint. Collateral ligament injury needs early treatment to prevent chronic laxity of the joint. Anterior cruciate ligament early reconstruction in top athletes results in their complete rehabilitation and return to the previous level performance. Total knee replacements may result in a number of complications, some of which need prompt treatment. Septic arthritis is a condition that requires prompt treatment, without any hesitation. Failure of earlier or prompt treatment of the conditions of the knee mentioned in this chapter may result in permanent damage to the knee joint.

Comparison of conventional spin-echo and fast spin-echo magnetic resonance imaging with fat suppression [correction for suppresion] in cruciate ligament injury.

AIM: To compare the quality and diagnostic reliability of conventional spin-echo and fast spin-echo with fat suppression magnetic resonance (MR) imaging in the evaluation of cruciate ligament injury. METHODS: Thirty-five patients with internal knee injury and positive clinical signs of cruciate ligament injury were examined by using an Elscint Prestige 2T MR scanner. Findings of conventional and fast spin-echo with fat suppression MR sequences were evaluated and compared with each other and with arthroscopic findings. In all patients, arthroscopy was performed within 2 months after the MR examination. RESULTS: Analysis of anterior cruciate ligament injury with conventional spin-echo sequence showed 81.8% sensitivity. The sensitivity of fast spin-echo sequences with fat suppression was 96.9%. According to the type of the anterior cruciate ligament injury, the sensitivity of fast spin-echo sequences with fat suppression was higher than that of conventional spin-echo sequence (85.7% and 66.7%, respectively) for partial rupture, but the sensitivity of both sequences for complete rupture was the same (100% both). CONCLUSION: Fast spin-echo with fat suppression sequence can be used routinely in clinical practice for the assessment of acutely injured knees as the substitute for conventional spin-echo sequence without decreased diagnostic reliability.

The incidence of injuries in elite junior figure skaters.

BACKGROUND: There has been rapid growth in the technical and physiologic demands made on skaters who perform more and more difficult jumps, spins, lifts, throws, and free skating movements. PURPOSE: To investigate the frequency of injuries and overuse syndromes in elite junior skaters. STUDY DESIGN: Questionnaire. METHODS: During four consecutive Junior World Figure Skating Championships and the Croatia Cup, we interviewed 236 female and 233 male skaters by questionnaire to determine the frequency of injuries and overuse syndromes. RESULTS: Fifty-nine of the female skaters (25%) and 65 of the male skaters (27.9%) reported sustaining acute injuries; 101 female (42.8%) and 106 male (45.5%) skaters reported overuse syndromes. Low back pain was reported by 19 female and 23 male skaters. The most frequent acute injury was ankle sprain. In singles female skaters, the most frequent overuse injury was stress fracture (19.8%), followed by jumper's knee (14.9%). In singles male skaters, jumper's knee (16.1%) was the most frequent injury, followed by Osgood-Schlatter disease (14.2%). More than 50% of injuries in young singles figure skaters involved overuse syndromes. Pairs skaters and ice dance skaters had a higher risk of acute injury than overuse syndrome because of falls from lifts and throw jumps. CONCLUSIONS: Programs to improve postural alignment, flexibility, and strength, especially during the asynchronous period of bone and soft tissue development, should be instituted to prevent and reduce overuse syndromes.