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OBJECTIVE: Tibial tubercle avulsion fractures (TTAFs) represent 0.4% to 2.7% of pediatric physeal injuries. These injuries are thought to confer a risk of acute compartment syndrome (ACS), and these patients are often admitted for compartment monitoring and, in many cases, undergo prophylactic fasciotomy. This study sought to review our institution's experience with TTAF and associated compartment syndrome in pediatric patients. METHODS: All patients aged 8 to 18 years with TTAF at our institution from January 1, 2017 to January 1, 2023 were retrospectively reviewed. Patient demographics, injury mechanism, fracture morphology, and postinjury course were reviewed. ACS was diagnosed by clinical exam or necessitating therapeutic compartment fasciotomy. RESULTS: A total of 49 TTAFs in 47 patients were included in the final analysis. The mean age was 14.5 ± 1.2 years (range: 11 to 17), and males were significantly older than females (14.6 ± 1.1 vs 13.3 ± 1.3 y, P = 0.01). The average body mass index was 27.1 ± 7.0, and males had a significantly lower body mass index than females (26.3 ± 6.5 vs 34.1 ± 8.5, P = 0.03). Basketball was the most common mechanism of injury (49%), followed by soccer (13%), football (11%), trampoline (6%), fall (6%), jumping (4%), lacrosse (4%), running (4%), and softball (2%). The Ogden fracture types were as follows: I: 10%; II: 16%; III: 41%; IV: 24%; V: 8%. Thirty-four patients (69%) were admitted to the hospital for at least one night after presentation. Forty-six (96%) underwent surgical fixation an average of 3.5 days after injury. No patients developed ACS during their post-injury or postoperative course. Three patients underwent the removal of hardware. No other complications were observed. The average follow-up duration was 238 days. CONCLUSIONS: The results of this study suggest that the risk of ACS in pediatric patients with TTAF may be small enough to allow for same-day discharge after diagnosis or operative management in patients deemed to be sufficiently low risk by clinical judgment. LEVEL OF EVIDENCE: Level III-retrospective comparative study.
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OBJECTIVES: This study aims to characterize the association between the timing of MRI ordering and completion for pediatric knee injuries and Social Deprivation Index (SDI), which is a comprehensive, validated, county-level, measure of socioeconomic variation in health outcomes based upon combining geography, income, education, employment, housing, household characteristics, and access to transportation. METHODS: A retrospective chart review was completed of patients 21 years old and younger from our institution with a history of knee sports injury (ligamentous/soft tissue injury, structural abnormality, instability, inflammation) evaluated with MRI between 5/26/2017 and 12/28/2020. Patients were from three states and attended to by physicians associated with an urban academic institution. Patients were assigned SDI scores based on their ZIP code. Excluded from the study were patients with a non-knee related diagnosis (hip, foot, or ankle), patients from ZIP codes with unknown SDI, and non-sports medicine diagnoses (tumor, infection, fracture). RESULTS: In a multivariate regression analysis of 355 patients, increased SDI was independently associated with increased time from clinic visit to MRI order (p = 0.044) and from clinic visit to MRI completion (p = 0.047). Each 10-point increase in SDI (0-100) was associated with a delay of 7.2 days on average. SDI itself was found to be associated with a patient's race (p < 0.001), ethnicity (p < 0.001), and insurance category (p < 0.001). CONCLUSION: Increased SDI is independently associated with longer time from clinic visit to knee MRI order and longer time from clinic visit to knee MRI completion in our pediatric population. Recognizing potential barriers to orthopedic care can help create the change necessary to provide the best possible care for all individual patients.
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BACKGROUND: A career in hand surgery in the United States requires a 1-year fellowship after residency training. Different residency specialty programs may vary in case volume. The purpose of this study was to characterize variation in hand surgery training within and between orthopaedic and plastic surgery residents. METHODS: Publicly available hand surgery case logs for graduating orthopaedic and plastic surgery residents during the 2010 to 2011 to 2018 to 2019 academic years were obtained through the Accreditation Council of Graduate Medical Education. Student t-tests were used to compare mean case volumes among several categories between plastic surgery (PRS) and orthopaedic surgery (OS) residents. Intraspecialty variation was assessed by comparing the 90th and 10th percentiles in each category. RESULTS: A total of 6,254 orthopaedic and 1,070 plastic surgery graduating residents were included. The mean hand surgery case volume for orthopaedic residents (OS 247.0) was significantly lower than that for plastic surgery residents (PRS 412.0) (P < 0.0001). Orthopaedic residents performed more trauma cases (OS 133.2, PRS 54.5; P < 0.0001) but fewer nerve repairs (OS 3.3, PRS 28.5 P < 0.0001) and amputations (OS 6.4, PRS 15.8; P < 0.0001). Nerve decompression case volumes were similar between the two specialties (OS 50.2, PRS 47.3; P = 0.34). Case volumes among orthopaedic residents varied considerably in amputations and among plastic surgery residents in replantation/revascularization procedures. CONCLUSIONS: Orthopaedic surgery residents performed significantly more trauma cases than plastic surgery residents did, but fewer overall cases, nerve repairs, and amputations, while nerve decompression volumes were similar between specialties. This information may help inform residency and fellowship directors regarding areas of potential training deficiency.
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Internado y Residencia , Procedimientos Ortopédicos , Ortopedia , Educación de Postgrado en Medicina , Mano/cirugía , Humanos , Ortopedia/educación , Estados UnidosRESUMEN
High complication rates associated with revision total knee arthroplasty (TKA) and total hip arthroplasty (THA) may unequally burden tertiary referral centers, which manage medically complex patients. The authors aimed to quantify TKA and THA referral patterns at a tertiary referral center based on travel distance and patient comorbidities. All patients who underwent primary or revision TKA or THA at the investigating institution from 2012 to 2016 were identified. Travel distance was calculated using each patient's home address and stratified into less than 25 miles, 25 to 74 miles, and 75 miles or more. Age, body mass index, Charlson Comorbidity Index, and postoperative clinical data were identified. Patients were analyzed based on procedure performed and travel distance. A total of 4245 procedures were included for analysis (1754 primary TKAs, 432 revision TKAs, 1503 primary THAs, and 556 revision THAs). Patients living 75 miles or more away had significantly higher odds of undergoing revision arthroplasty compared with patients living within 25 miles (knee: odds ratio [OR], 2.43; hip: OR, 2.61; P<.001). Charlson Comorbidity Index did not increase with travel distance. Patients traveling 75 miles or more were more likely to have periprosthetic fracture (OR, 3.91; P=.011) and less likely to have dislocation (OR, 0.54; P=.026) as the surgical indication for revision. Patients referred to a tertiary center were more likely to necessitate revision total joint arthroplasty but did not differ in comorbidity profile compared with local patients. Periprosthetic fracture, a particularly high-risk surgical indication, was overrepresented among referral patients. These data suggest that factors such as underlying diagnosis, but not preoperative medical comorbidities, may influence referral patterns. [Orthopedics. 2021;44(4):e477-e481.].
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Artroplastia de Reemplazo de Cadera , Artroplastia de Reemplazo de Rodilla , Fracturas Periprotésicas , Artroplastia de Reemplazo de Cadera/efectos adversos , Artroplastia de Reemplazo de Rodilla/efectos adversos , Humanos , Fracturas Periprotésicas/cirugía , Reoperación , Estudios Retrospectivos , Factores de Riesgo , Centros de Atención TerciariaRESUMEN
Numerous studies have explored 90-day readmissions following total joint arthroplasty; however, there is a paucity of literature concerning 90-day emergency department (ED) visits. The authors aimed to characterize the risk factors for ED presentations and to determine the primary reasons for return, hypothesizing that certain medical comorbidities would account for resource utilization. The institutional database was queried for primary total hip arthroplasty (THA) and total knee arthroplasty (TKA). Patients were stratified based on return visits to the ED within 90 days postoperatively. Univariable and multivariable analyses were performed to determine the factors most predictive of ED return for each THA and TKA. A total of 10,479 procedures resulted in 1234 90-day ED visits made by 937 patients. Significant predictors of 90-day ED return after THA included black race, age older than 80 years, congestive heart failure, valvular heart disease, metastatic disease, peripheral vascular disease, alcoholism, drug use, depression, and discharge to a skilled nursing facility. In contrast, only black race, liver insufficiency, cancer, and pulmonary hypertension were predictive of ED return following TKA. The primary risk factors for ED return differ for THA and TKA, and this is not currently reflected in the medical severity diagnosis-related group system. Specifically, black patients with multiple comorbidities are at high risk for unplanned ED visits following THA. This should be considered in patient counseling and outreach programs when attempting to mitigate the postoperative risks and to decrease 90-day resource utilization in this patient population. [Orthopedics. 2020;43(5):295-302.].
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Artroplastia de Reemplazo de Cadera/efectos adversos , Artroplastia de Reemplazo de Rodilla/efectos adversos , Servicio de Urgencia en Hospital , Alta del Paciente , Readmisión del Paciente , Factores de Edad , Anciano , Bases de Datos Factuales , Femenino , Humanos , Masculino , Persona de Mediana Edad , Periodo Posoperatorio , Medición de Riesgo , Factores de RiesgoRESUMEN
BACKGROUND: Selective serotonin reuptake inhibitors (SSRIs) have been shown in both orthopedic and general surgery literature to be associated with an increased risk of blood loss, and this is thought to occur via diminished platelet serotonin reuptake and subsequent decline in platelet aggregation potential. In this study, we aim at quantifying the effect of treatment with SSRIs on blood loss and transfusion rates following total hip (THA) or total knee arthroplasty (TKA). METHODS: THA (4485) and TKA (5584) cases from January 2013 to December 2017 at the investigating institution were queried and analyzed separately from an institutional database. Patients were stratified by utilization of an SSRI at the time of surgery. Patient demographics, baseline coagulopathy, preoperative and postoperative hemoglobin, transfusion, and length of stay were obtained to compare the 2 cohorts. RESULTS: The transfusion rate for SSRI users was 3.9% in the TKA group and 8.5% in the THA group. After controlling for age, gender, body mass index, presence of coagulopathy, procedure (THA vs TKA), and SSRI status, SSRI utilization was significantly associated with increased blood loss (P < .004), and logistic regression controlling for the same variables showed SSRI utilization to be predictive of transfusion (odds ratio, 1.476; P < .001). CONCLUSION: SSRI utilization was associated with increased perioperative blood loss and predictive of transfusion risk, particularly with THA. This represents an important factor that may be modified in the setting of total joint arthroplasty but further work will be necessary to study potential alternative medications for depression in the perioperative phase.
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Artroplastia de Reemplazo de Cadera , Artroplastia de Reemplazo de Rodilla , Transfusión Sanguínea , Inhibidores Selectivos de la Recaptación de Serotonina/efectos adversos , Humanos , Estudios Retrospectivos , Factores de RiesgoRESUMEN
Two-stage exchange is most commonly used for treatment of prosthetic joint infections (PJI) but, this may fail to eradicate infections. C-reactive protein/albumin ratio (CAR) has been used to predict survival and operative success in other surgical subspecialties and so, we assess the association between CAR and reimplantation success during two-stage revision for PJI defined by the Musculoskeletal Infection Society following a primary total hip (THA) or knee (TKA) arthroplasty. From January, 2005 to December, 2015, two institutional databases were queried and patient demographics, antibiotic duration, C-reactive protein, and albumin were collected prior to reimplantation. Two-stage revisions were considered successful if patients were off of antibiotics and did not require a repeat surgery. CAR was available for 79 patients (34 hips and 46 knees) with 61 successful two-stage revisions and 18 failures. The average CAR for patients with successful reimplantation was 1.2 (0.2, 3.0) compared to 1.0 (0.4, 3.2) for treatment failure. However, this was not statistically significant (p=0.766). Therefore, CAR is not applicable in predicting the prognosis of two-stage revisions for PJI in total arthroplasty but other preoperative inflammatory-based prognostic scores should be explored.
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Transient osteoporosis is a rare manifestation of acute hip pain which typically resolves with weight-bearing restrictions and pain management. Our case report presents a patient who experienced atraumatic right hip pain a few weeks after an uncomplicated bariatric surgery and was diagnosed with transient osteoporosis of the hip. Her condition resolved after weeks of protected weight-bearing restrictions and nonsteroidal anti-inflammatories. Transient osteoporosis should be considered in the differential diagnosis of hip pain in patients who have undergone previous bariatric surgery.
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BACKGROUND: Current Procedural Terminology coding currently makes no distinction between primary total knee arthroplasty (TKA) and conversion TKA, in which periarticular hardware components must be removed prior to or during TKA. We hypothesize that conversion TKA will carry increased operative time, blood loss, postoperative complications, and 90-day emergency department/readmission rate compared to primary TKA. METHODS: Patients undergoing conversion TKA from 2005 to 2017 were identified from an institutional database and matched to primary TKA patients by age, gender, American Society of Anesthesiologists score, body mass index, and procedure date (±1 year). Intraoperative data and 90-day postoperative complications were compared between groups. RESULTS: One hundred nine conversion TKA patients with periarticular hardware were removed prior to (n = 51) or during (n = 58) TKA and 109 primary TKA control patients were included. Conversion TKA was associated with increased tourniquet time (91 vs 71 minutes, P < .001), operative time (147 vs 113 minutes, P < .001), blood loss (225 vs 176 mL, P = .010), 90-day readmissions (14.6% vs 4.2%, P = .020), wound complication (5.6% vs 0.0%, P = .025), periprosthetic joint infection (7.9% vs 0.0%, P = .005), irrigation/debridement (9.0% vs 1.1%, P = .016), and a trend toward increased mechanical complication (6.7% vs 1.1%, P = .058). Timing of hardware removal did not affect intraoperative or postoperative outcomes. CONCLUSION: Conversion TKA is associated with higher operative time, blood loss, readmission rate, and postoperative complications compared to primary TKA. Without a proper billing code and appropriate reimbursement level to match the expected operative and postacute resource utilization by these cases, physicians may be disincentivized to perform these operations.
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Artroplastia de Reemplazo de Rodilla/efectos adversos , Artroplastia de Reemplazo de Rodilla/métodos , Complicaciones Posoperatorias/etiología , Anciano , Artroplastia de Reemplazo de Rodilla/economía , Índice de Masa Corporal , Femenino , Costos de la Atención en Salud , Humanos , Masculino , Persona de Mediana Edad , Tempo Operativo , Osteotomía/economía , Osteotomía/métodos , Complicaciones Posoperatorias/economía , Periodo Posoperatorio , Riesgo , Tibia/cirugíaRESUMEN
Retinal photoreceptors are important in visual signaling for normal eye growth in animals. We used Gnat2cplf3/cplf3 (Gnat2-/-) mice, a genetic mouse model of cone dysfunction to investigate the influence of cone signaling in ocular refractive development and myopia susceptibility in mice. Refractive development under normal visual conditions was measured for Gnat2-/- and age-matched Gnat2+/+ mice, every 2 weeks from 4 to 14 weeks of age. Weekly measurements were performed on a separate cohort of mice that underwent monocular form-deprivation (FD) in the right eye from 4 weeks of age using head-mounted diffusers. Refraction, corneal curvature, and ocular biometrics were obtained using photorefraction, keratometry and optical coherence tomography, respectively. Retinas from FD mice were harvested, and analyzed for dopamine (DA) and 3,4-dihydroxyphenylacetate (DOPAC) using high-performance liquid chromatography. Under normal visual conditions, Gnat2+/+ and Gnat2-/- mice showed similar refractive error, axial length, and corneal radii across development (pâ¯>â¯0.05), indicating no significant effects of the Gnat2 mutation on normal ocular refractive development in mice. Three weeks of FD produced a significantly greater myopic shift in Gnat2-/- mice compared to Gnat2+/+ controls (-5.40⯱â¯1.33 D vs -2.28⯱â¯0.28 D, pâ¯=â¯0.042). Neither the Gnat2 mutation nor FD altered retinal levels of DA or DOPAC. Our results indicate that cone pathways needed for high acuity vision in primates are not as critical for normal refractive development in mice, and that both rods and cones contribute to visual signalling pathways needed to respond to FD in mammalian eyes.
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Miopía/fisiopatología , Retina/fisiopatología , Células Fotorreceptoras Retinianas Conos/patología , Ácido 3,4-Dihidroxifenilacético/metabolismo , Animales , Cromatografía Líquida de Alta Presión , Modelos Animales de Enfermedad , Susceptibilidad a Enfermedades , Dopamina/metabolismo , Femenino , Proteínas de Unión al GTP Heterotriméricas/genética , Masculino , Ratones , Ratones Endogámicos C57BL , Miopía/metabolismo , Refracción Ocular/fisiología , Retina/metabolismo , Privación Sensorial , Tomografía de Coherencia Óptica , Agudeza Visual/fisiologíaRESUMEN
BACKGROUND: Choosing the intervention for prosthetic joint infections, whether debridement, antibiotics, and implant retention (DAIR), or explant and antibiotic spacer placement, is multifactorial. One characteristic that may influence this decision is a previously established relationship with the patient. We hypothesized that patients receiving their arthroplasty at an outside institution and presenting with infection would be more likely to undergo removal of their implant without an attempt at DAIR compared to patients who underwent primary arthroplasty at the investigating institution. METHODS: The institutional database was queried for primary total hip and knee arthroplasty infections. Manual review of medical records was performed, excluding patients who did not meet the Musculoskeletal Infection Society definition of infection. Patient demographics, medical comorbidities, presenting infection characteristics, and surgical intervention were collected. Multivariable analysis was performed to determine the independent predictors of treatment. RESULTS: A total of 270 patients were included for analysis. McPherson score (P < .001) and duration of symptoms (P < .001) were associated with subsequent treatment. Additionally, when controlling for age, gender, symptom duration category, procedure, McPherson score, and American Society of Anesthesiologists category, patients with index procedures at outside hospitals were more likely to undergo implant removal (odds ratio, 36.30; 95% confidence interval, 8.16-161.51; P < .001). CONCLUSION: Patients receiving their primary arthroplasty at an outside hospital and presenting with infection are more likely to undergo removal of hardware as their initial treatment. To avoid treatment bias, institutional protocols should be implemented to guide the shared decision-making process.
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Artritis Infecciosa/cirugía , Toma de Decisiones Clínicas , Desbridamiento/estadística & datos numéricos , Remoción de Dispositivos/estadística & datos numéricos , Infecciones Relacionadas con Prótesis/cirugía , Anciano , Antibacterianos/uso terapéutico , Artritis Infecciosa/tratamiento farmacológico , Artroplastia de Reemplazo de Cadera/efectos adversos , Artroplastia de Reemplazo de Rodilla/efectos adversos , Femenino , Prótesis de Cadera/efectos adversos , Humanos , Prótesis de la Rodilla/efectos adversos , Masculino , Persona de Mediana Edad , Oportunidad Relativa , Infecciones Relacionadas con Prótesis/tratamiento farmacológico , Estudios Retrospectivos , Resultado del TratamientoRESUMEN
BACKGROUND: At the investigating institution, an electronic messaging portal (MyChart) allows patients to directly communicate with their healthcare provider. As reimbursement models evolve, there is an increasing effort to decrease 90-day hospital resource utilization and patient returns, and secure messaging portals have been proposed as one way to achieve this goal. We sought to determine which patients utilize this portal, and to determine the impact of secure messaging on emergency department (ED) visits and readmissions within 90 days postoperatively. METHODS: The institutional database was used to analyze 6426 procedures including 3297 primary total knee and 3129 primary total hip arthroplasties. Patient demographics, comorbidities, and secure communication activity status were recorded. Subsequently, statistical analysis was performed to determine which patients utilized MyChart, as well as to correlate patient outcomes to the utilization of secure messaging portals. RESULTS: Active MyChart users were significantly more likely to be young, healthy (American Society of Anesthesiologists 1 or 2), Caucasian, married, employed, have private insurance, and be discharged to home. Decreased utilization was seen in patients who were unhealthy (American Society of Anesthesiologists 3 or 4), were African American, unmarried, unemployed, had Medicare or Medicaid insurance, and were discharged to a skilled nursing facility; these characteristics were also independent significant risks for returning to the ED. Active MyChart status was not significantly associated with 90-day ED return (P = .781) or readmission (P = .512). However, if multiple messages to providers were sent, and the provider response rate was <75%, patients had significantly more readmissions (P = .004). CONCLUSION: Primary total joint arthroplasty patients who were at high risk for ED returns were less likely to utilize MyChart. However, MyChart use did not decrease the 90-day rate of return to the ED or readmissions. A low provider response rate to the secure messages may lead to increased resource utilization in patients using secure messaging as their preferred communication tool. Alternative means of communication with the most vulnerable patients must be investigated to effectively decrease postoperative complications and resource utilization.
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Artroplastia de Reemplazo de Cadera/rehabilitación , Artroplastia de Reemplazo de Rodilla/rehabilitación , Servicio de Urgencia en Hospital/estadística & datos numéricos , Portales del Paciente/estadística & datos numéricos , Readmisión del Paciente/estadística & datos numéricos , Anciano , Bases de Datos Factuales , Femenino , Humanos , Masculino , Medicare , Persona de Mediana Edad , Alta del Paciente , Periodo Posoperatorio , Instituciones de Cuidados Especializados de Enfermería , Estados UnidosRESUMEN
BACKGROUND: Left common iliac vein (LCIV) compression by the right or left common iliac artery (RCIA, LCIA) is known to cause venous thromboembolism (VTE), but the extent to which occult LCIV compression synergizes with lower extremity orthopedic surgery is unknown. We hypothesize that occult LCIV compression is associated with increased VTE risk following total hip or knee arthroplasty (THA, TKA). METHODS: This case-control study involves all patients at our institution who underwent primary or revision THA or TKA from 2009 to 2017 who had computed tomography or magnetic resonance imaging of the abdomen or pelvis available preoperatively. VTE cases (pulmonary embolism or left-sided deep vein thrombosis) within 30 days of surgery were matched to a control by age, gender, body mass index, Charlson Comorbidity Index, surgical site, and hypercoagulable risk factors. LCIV compression by the right common iliac artery and/or the left common iliac artery was measured in a blinded fashion and was considered present at 50% diameter reduction. RESULTS: One hundred twelve patients (22 cases, 90 controls) were included for analysis. Nineteen (86.4%) cases and 46 (51.1%) controls demonstrated LCIV compression. The overall sample odds ratio of postoperative VTE in the presence of LCIV compression was 5.97 (95% confidence interval 1.59-33.67, P = .003). In patients who underwent THA (n = 75), LCIV compression was highly predictive of VTE (odds ratio ∞, 95% confidence interval 2.83-∞, P < .001). Compression in the TKA patients did not significantly predict VTE. CONCLUSION: Compression of the LCIV significantly increases odds of developing postoperative VTE following THA. This effect may suggest a new method of stratifying VTE risk in the orthopedic population to reduce VTE-associated morbidity and mortality.
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Artroplastia de Reemplazo de Cadera/efectos adversos , Artroplastia de Reemplazo de Rodilla/efectos adversos , Arteria Ilíaca , Vena Ilíaca , Complicaciones Posoperatorias/etiología , Tromboembolia Venosa/etiología , Estudios de Casos y Controles , Humanos , Imagen por Resonancia Magnética , Oportunidad Relativa , Periodo Posoperatorio , Embolia Pulmonar/etiología , Factores de Riesgo , Tomografía Computarizada por Rayos X , Trombosis de la Vena/etiologíaRESUMEN
PURPOSE: The neuromodulator dopamine (DA) has been implicated in the prevention of excessive ocular elongation and myopia in various animal models. This study used retina-specific DA knockout mice to investigate the role of retinal DA in refractive development and susceptibility to experimental myopia. METHODS: Measurements of refractive error, corneal curvature, and ocular biometrics were obtained as a function of age for both untreated and form-deprived (FD) groups of retina-specific tyrosine hydroxylase knockout (rTHKO) and control (Ctrl) mice. Retinas from each group were analyzed by HPLC for levels of DA and its primary metabolite (DOPAC). RESULTS: Under normal visual conditions, rTHKO mice showed significantly myopic refractions (F(1,188) = 7.602, P < 0.001) and steeper corneas (main effect of genotype F(1,180) = 5.1, P < 0.01) at 4 and 6 weeks of age compared with Ctrl mice. Retina-specific THKO mice also had thinner corneas (main effect of genotype F(1,181) = 37.17, P < 0.001), thinner retinas (F(6,181) = 6.07, P < 0.001), and shorter axial lengths (F(6,181) = 3.78, P < 0.01) than Ctrl mice. Retina-specific THKO retinas contained less than 15% of DA and DOPAC compared with Ctrl retinas, and the remaining DA had a significantly higher turnover, as indicated by DOPAC/DA ratios (Student's t-test, P < 0.05). Retina-specific THKO mice showed similar, yet more variable, responses to 6 weeks of FD compared with Ctrl mice. CONCLUSIONS: Diminished retinal DA induced spontaneous myopia in mice raised under laboratory conditions without form deprivation. The relative myopic shift in rTHKO mice may be explained by steeper corneas, an unexpected finding. The chronic loss of DA did not significantly alter the FD myopia response in rTHKO mice.