Does medullary diameter to stem width ratio and stem length affect outcomes of revision total knee arthroplasties? A case series.

OBJECTIVES: This study aimed to investigate the relationship between the ratio of stem size to intramedullary canal diameter, stem length, and functional outcome in revision total knee arthroplasty (RTKA) procedures, which remains largely unexplored in the current literature. PATIENTS AND METHODS: A single surgeon series of RTKA procedures performed between October 2014 and November 2022 were included in this case series, and data were analyzed retrospectively. A total of 32 patients (27 females, 5 males; mean age: 73.2±8.1 years; range, 52 to 88 years) were identified, with a minimum follow-up period of five months and a maximum of eight years. Filtering the patients based on >24 month follow-up, we were left with 13 patients aged between 65 and 88 (mean 74.9±6.9) years. The latest X-rays of patients were analyzed, and the ratio of intramedullary canal diameter to stem width was calculated for both femur and tibia in both anteroposterior and lateral planes. Household income, preoperative C-reactive protein, erythrocyte sedimentation rate, comorbidities, body mass index, and implant dimensions were also recorded. Postoperative Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Short Form-12 (SF-12) scores, and range of motion (ROM) measurements were used to evaluate functional outcome. RESULTS: A moderate negative relationship between the tibial canal fill ratio (CFR) in anteroposterior views and ROM of the patients was noted. Additionally, a significant positive correlation was found between SF-12 physical score and CFR in lateral view. A moderate level of correlation between femoral CFR in anteroposterior views was also established. Due to insufficient data, joint ROM data did not show normal distribution. Therefore, a cutoff value indicating the relationship between the stem size and knee ROM could not be calculated using receiver operating characteristic analysis. Multiple regression analysis did not yield significant results, suggesting that hypothesized predictor variables were not sufficient to predict the variation in functional scores. Otherwise, no clear statistical importance or correlation between functional scores, such as WOMAC or SF-12, and CFR was found. CONCLUSION: In conclusion, the findings suggest that other factors, such as other patient characteristics, surgical techniques, or implant designs, may have a more substantial impact on the functional outcomes in RTKA patients.

Ultrasonography Causes Agitation and Pain Leading to Hemodynamic Disturbance in Neonates: A Prospective Observational Study.

BACKGROUND: Ultrasonography is widely used in neonatological practice and studies investigating the hemodynamic effects of various treatment protocols or clinical situations. On the other hand, pain causes changes in the cardiovascular system; so, in the case of ultrasonography leading to pain in neonates, it may cause hemodynamic alterations. In this prospective study, we evaluate whether ultrasonographic application causes pain and changes in the hemodynamic system. METHODS: Newborns undergoing ultrasonographic examination were enrolled in the study. Vital signs, cerebral and mesenteric tissue oxygenation (StO2) levels, and middle cerebral artery (MCA) Doppler measurements were recorded, and NPASS scores were calculated before and after ultrasonography. RESULTS: We enrolled 39 patients in the study. After ultrasonography, Neonatal Pain, Agitation, and Sedation Scale (NPASS) scores were significantly higher (p < 0.01), and all vital signs (heart rate, respiratory rate, SpO2, diastolic and systolic blood pressure; p = 0.03; p < 0.01, p < 0.01, p < 0.01, p = 0.02, p = 0.03, respectively) were altered. Cerebral (p = 0.008) and mesenteric (p = 0.039) StO2 levels were significantly lower in the whole study group, MCA end-diastolic velocity decreased (p = 0.02), and the resistive index (p = 0.03) increased in patients whose NPASS score was >7 after ultrasonography. CONCLUSIONS: This study is the first to show that ultrasonography may cause pain in newborn patients, and alters vital signs and hemodynamic parameters. Therefore, precautions should be taken to protect newborn babies from pain during ultrasound applications, as they are already exposed to many noxious stimuli. Furthermore, pain scores should be considered in studies using ultrasonography and evaluating hemodynamic parameters to increase the reliability of the studies.

Radiographic assessment of bone tunnels after anterior cruciate ligament reconstruction: A comparison of hamstring tendon and bone-patellar tendon-bone autografting technique.

OBJECTIVES: This study aims to compare the postoperative change of femoral and tibial tunnel widths after hamstring tendon (HT) and bone-patellar tendon-bone (BPTB) autografting in primary anterior cruciate ligament (ACL) reconstruction surgery with the anteromedial portal technique. PATIENTS AND METHODS: This case-control and retrospective study included 39 patients (36 males, 3 females; mean age 30.1±7.9; range, 17 to 44 years) who underwent primary ACL reconstruction surgery with either BPTB autografting method (BPTB group, n=18) or HT autografting method (HT group, n=21) between March 2014 and December 2016. Femoral fixation was achieved with bioabsorbable screw in BPTB group and endobutton in HT group. Tibial fixation was achieved with bioabsorbable interference screw in both groups. Femoral and tibial tunnel widths of groups were compared on digital radiographs. RESULTS: When we compared the baseline values with the second-year results, the mean of femoral tunnel widths were significantly lower on radiographs at the second-year evaluation in both groups (p<0.001 for all). However, the means of tibial tunnel widths were significantly lower only in the BPTB group (p<0.001 for BPTB group and p=0.616 for HT group). Change levels of anteroposterior and lateral widths were more prominent in BPTB group than HT group (p<0.001 for all). CONCLUSION: Changes in tunnel widths show us superior ossification in BPTB grafting. This can be explained by superior bone-to-bone healing. As a result of radiological evaluation, we think that BPTB grafting can be more strong and durable.

Correction to: Patella-patellar tendon angle and lateral patella-tilt angle decrease patients with chondromalacia patella.

The original article can be found online.

Is iliac autogenous graft augmentation in medial open wedge high tibial osteotomies superior to no augmentation in terms of bone healing?

OBJECTIVES: This study aims to investigate if iliac autogenous graft augmentation in medial open wedge high tibial osteotomies (OWHTOs) is superior to no augmentation in terms of bone healing. PATIENTS AND METHODS: Twenty-five patients (14 males, 11 females; mean age 40.9±4.0 years; range, 33 to 48 years) with medial compartmental osteoarthritis of knee joint who underwent high tibial osteotomy with medial open wedge between January 2016 and December 2018 were included in this retrospective study. Twelve of the operated knees were the right knee. Graft was used in 13 patients (52%). Data including age, gender, body mass index (BMI), direction, follow-up period, union, Lysholm and International Knee Documentation Committee (IKDC) scores, pre- and postoperative femoral tibial angles (FTAs) and posterior tibial slopes were evaluated. RESULTS: The mean BMI was 26.4±1.9 (range, 22.0 to 30.0). Only 48% of the patients were smoking. The mean follow-up period was 28.6±5.3 months (range, 24 to 38 months). No statistically significant difference was found between the grafted and non-grafted groups in terms of age, BMI, follow-up time, gender, side and smoking status (p>0.05) There was no statistically significant difference between two groups in terms of pre- and postoperative Lysholm scores, pre- and postoperative IKDC scores, or pre- and postoperative FTA values (p>0.050). CONCLUSION: Iliac autogenous graft augmentation in medial OWHTO has no effect on union but shortens the union time. Preoperative high varus degree adversely affects union. Therefore, routine use of iliac crest autograft is not recommended.

Patella-patellar tendon angle and lateral patella-tilt angle decrease patients with chondromalacia patella.

PURPOSE: The aim of the present study was to evaluate the effect of patellofemoral joint morphology and patellar alignment (lateral patellar tilt and sagittal patellar tilt) on the presence and stage of CP, and identify the differences between sexes. METHODS: MRI of 243 patients [146 men (60.1%)] were evaluated retrospectively. Patients were grouped as normal group without chondromalacia, group with mild chondromalacia (grades 1-2) and group with severe chondromalacia (grades 3-4). Sagittal patellofemoral alignment was assessed by the angle between the patella and patellar tendon (P-PTA), and the angle between the quadriceps tendon and patella (Q-PA). Patellar tilt was assessed by lateral patellar tilt angle (LPTA). In addition, patellofemoral joint morphology was evaluated by measuring trochlear depth (TD), trochlear sulcus angle (TSA) and patella angle (PA). RESULTS: P-PTA, Q-PA, LPTA and TD values were significantly lower in patients with severe chondromalacia than in patients with both normal and mild chondromalacia (P < 0.001). TSA values were significantly higher in patients with severe chondromalacia than those with both normal and mild chondromalacia (P < 0.001). TSA was higher and TD was lower in women compared to men (P < 0.001). LPTA and P-PTA were lower in women compared to men, and the difference was significant. There was no difference in PA between the two sexes. CONCLUSIONS: Patellar cartilage degeneration increases with trochlear dysplasia. There is a strong correlation between patellar malalignment (lateral patellar tilt and sagittal patellar tilt) and chondromalacia patella. Women are more prone to developing CP than men.

The Relationship Between Nasal Septal Deviation and Paranasal Pneumatization.

OBJECTIVE: To investigate the impact of the presence and the severity of the nasal septal deviation (NSD) on the paranasal pneumatization. METHODS: Initially, the deviated and contralateral sides was compared to evaluate the impact of the presence of NSD on pneumatization. Then, NSD classification groups were categorized according to the severity of deviation degree; 1: mild (<9°), 2: moderate (9°-15°), and 3: severe (>15°). Pneumatization of all paranasal sinuses, osteomeatal complex (OMC), frontoethmoid recess (FER) and variant structures were compared according to the NSD classification groups separately both for the deviated and the contralateral sides. RESULTS: Although there was no statistically significant difference in pneumatization of the paranasal sinuses between the deviated and contralateral sides, a significant difference was observed in OMC and FER diameters. In the deviated side, there was statistically significant difference in ethmoid sinus volume, in FER and OMC diameters between NSD classification groups. In the contralateral side, FER and OMC diameters were found to be significantly different between group 1 and group 2 and between group 1 and group 3, respectively (P = 0.04 and 0.06, respectively). Both the presence and severity of the NSD did not statistically significant influence the pneumatization of variant structures, air cells and vital structures. CONCLUSION: The severity of NSD effects the ethmoid sinus volume. The relationship of FER and OMC with NSD is evident, however this may not always be in a proportional pattern. The paranasal pneumatization did not affect Keros type, bone integrity of carotid canal and optic canal.

Higher Body Mass Index Adversely Affects Knee Function After Anterior Cruciate Ligament Reconstruction in Individuals Who Are Recreationally Active.

OBJECTIVE: Our aim was to investigate the effect of body mass index (BMI) levels on quadriceps and hamstring strength and functional outcomes up to 6 months after anterior cruciate ligament reconstruction (ACLR) with hamstring tendon autograft (HTG). DESIGN: Prospective, controlled study. SETTING: University clinical laboratory. PATIENTS: Ninety-one participants who had undergone unilateral ACLR with HTG were divided into 2 groups according to their BMI. The participants whose BMI were between 18.5 and 24.9 kg/m were included in group 1 (n = 50, age: 27.2 ± 6.7 years, BMI: 22.3 ± 1.6 kg/m) and those whose BMI > 24.9 kg/m were included in group 2 (n = 41, age: 30.2 ± 6.9 years, BMI: 28.0 ± 2.4 kg/m). INTERVENTIONS: Quadriceps and hamstring strength, functional performance including hop, jump, and balance performance, and IKDC score. MAIN OUTCOME MEASURES: Maximum voluntary isometric contraction of the quadriceps and hamstring muscles and the body mass were measured at 1, 3, and 6 months after surgery. Absolute peak torques and normalized peak torques to body weight for both limbs were recorded. Functional outcomes were evaluated at 6 months after surgery. RESULTS: Normalized quadriceps strength improvement was lower in group 2 when compared with group 1 (F(2,178) = 6.23, P = 0.003). Group 2 also demonstrated lower scores in functional performance (P < 0.05). Normalized hamstring and absolute quadriceps and hamstring strength improvement was not affected by higher BMI level (P > 0.05). CONCLUSIONS: Higher BMI levels adversely affect quadriceps strength capacity and performance in patients who have undergone ACLR with HTG. Clinicians should consider BMI levels of patients when assessing and targeting muscle recovery because it could negatively affect the success of the ACLR rehabilitation.

A comprehensive ultrasonographic investigation of the common flexor tendon and medial epicondyle in asymptomatic individuals.

AIM: To investigate the common flexor tendon (CFT) thickness and the frequency of ultrasound (US) pathological alterations in its structure in a healthy population and to evaluate if these findings can be correlated with dominant hand, age, gender, body mass index, workload, menopause status. MATERIAL AND METHODS: The study population consisted of 111 healthy volunteers. Bilateral CFT thicknesses were measured at 5 mm, 10 mm and 15 mm distance to medial epicondyle. Tendon echotexture, tears, calcification, enthesophyte, and neovascularization were also evaluated. RESULTS: The CFT was thicker on the dominant side at all three locations (2.1 versus 1.9 mm proximal, 4.0 versus 3.7 mm in the middle and 7.0 versus 6.6 mm distal, all p<0.05). Thickness correlated negatively with postmenopausal duration in all landmarks, except for the nondominant side distal part and positive with body mass index, significantly on the dominant side proximal and middle parts. A statistically significant correlation was found between heavy workers group and tendon thicknesses on the proximal and middle parts of the dominant side and the distal part of the non-dominant sides. US tendinosis was detected in 24/222 tendons, calcification in 11/222 tendons and enthesophyte in 33/222 tendons. The threshold age was 46.5 years for enthesophytes and 51.5 years for calcifications. The prevalence of calcification and enthesophyte tended to be higher in blue-collar workers and on the dominant side. CONCLUSIONS: The CFT thickness varies depending on measurement locations, handedness, body mass index, postmenopausal duration and workload. The US signs of tendinosis may be encountered in a symptom-free population. Calcification and enthesophyte tended to be more frequent in blue-collar workers.

Self-reported outcomes are associated with knee strength and functional symmetry in individuals who have undergone anterior cruciate ligament reconstruction with hamstring tendon autograft.

BACKGROUND: The aim of this study was to investigate the relationship between self-reported knee outcomes and limb symmetry indices (LSIs) for hip and knee strength, postural control and single-leg hop distance in individuals who had undergone an anterior cruciate ligament (ACL) reconstruction via hamstring tendon autograft (HTG). METHODS: A total of 72 participants with a history of unilateral ACL reconstruction via HTG (mean ±â€¯standard deviation (SD) age: 28.0 ±â€¯7.6 years; height: 178.4 ±â€¯6.7 cm; mass 76.9 ±â€¯14.9 kg) were included. International Knee Documentation Committee 2000 Subjective Knee Form (IKDC), Lysholm, Knee Osteoarthritis Outcomes Scores (KOOS) and Tampa scores were used to evaluate self-reported outcomes. Concentric and eccentric knee extensor and flexor, and hip strength, postural control and single leg hop distance were evaluated for performance-based outcomes. The relationships between the LSI scores and the performance measures were explored using the Pearson correlation coefficient. RESULTS: The IKDC, Lysholm and KOOS scores were positively correlated with knee extensor and flexor strength LSIs (P < 0.05, r = 0.34 to r = 0.50), and the Tampa score was negatively correlated with eccentric extensor LSI (P = 0.02, r = -0.34). Single-leg hop distance LSI was correlated with IKDC and Lysholm scores (P = 0.003, r = 0.50; P = 0.04, r = 0.29) respectively, while postural control was only correlated with the KOOS scores (P < 0.001, r = 0.51 to r = 0.52). CONCLUSIONS: Compared to Lysholm and Tampa scores, KOOS and IKDC scores were more likely to be correlated with performance-based outcomes. Therefore, KOOS and IKDC scores may help clinicians in return to sport decision making when there is a limited time to perform extensive evaluations or access equipment.

Radiological and functional comparison of single-bundle anterior cruciate ligament reconstruction: transtibial versus anteromedial technique

Background/aim: This study aimed to compare radiological and functional outcomes of patients who had single-bundle anterior cruciate ligament (ACL) reconstruction with autologous hamstring tendon grafts using transtibial (TT) versus anteromedial (AM) femoral tunnel drilling techniques. Materials and methods: Sixty patients who had been operated on between 2010 and 2013 were enrolled in this study. Tunnel positions and widenings in the femur and tibia were evaluated with radiographs, arthrometric measurements with a Rolimeter arthrometer (Aircast, Summit, NJ, USA), stability assessment with Lachman and reverse pivot shift tests, and functional assessment with the International Knee Documentation Committee and Tegner and Lysholm scoring systems. Results: Tunnel enlargement in the sagittal and coronal planes of the femur was higher with the TT technique (P < 0.0001) and that of the coronal planes of the tibia was also higher with the TT technique (P = 0.01). During the assessment with the Rolimeter, the difference between sides was significant with the TT technique (P = 0.013). Positive results of the Lachman and reverse pivot shift tests were more frequent with the TT technique (P < 0.05), and the Lysholm scores were higher with the AM technique (P = 0.001). Conclusion: ACL reconstruction with hamstring autografts by either TT or AM technique demonstrated similar and excellent results in terms of functional outcomes at the end of the first postoperative year. The TT group had increased tunnel enlargement, which may have uncertain long-term outcomes, compared with the AM group.

Short-Term Results of Flexor Hallucis Longus Transfer in Delayed and Neglected Achilles Tendon Repair.

Flexor hallucis longus (FHL) tendon transfer to the calcaneus in the repair of delayed or neglected Achilles tendon (AT) injuries is a viable and dynamic option. Nineteen patients (18 males, 1 female; mean age 47.4 ± 12.4, range 24 to 74, years; body mass index 27.5 ± 4.5, range 23.2 to 38.9, kg/m2; interval from injury to surgery 40.8 ± 11.6, range 28 to 60, days) with delayed or neglected repair of AT rupture were included in the present study. FHL transfer to the calcaneus through a single incision and repair of the defect with native tendon lengthening or a tendinous turndown flap was performed. American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot and hallux scale scores, balance and jump performance, ankle dorsiflexion range of motion, and lower extremity concentric and eccentric strength were evaluated 6 months postoperatively. Student's t test was used to compare the outcomes between the operated and nonoperated sides. AOFAS hindfoot and hallux scale scores were 93.83 and 86.9, respectively. No significant difference was found in vertical jump (p = .60), forward jump (p = .68), or balance performance (p > .05). However, less ankle dorsiflexion on the operated side was recorded compared with the nonoperated side (p = .008). Concentric/eccentric muscle strength between the operated and nonoperated side was similar (p > .05). The concentric strength of the operated side reached 92% and eccentric strength reached 101.7% of the nonoperated side's strength. All the patients were satisfied with their results and return to preinjury daily activities. AT repair of a delayed and neglected injury using FHL transfer to the calcaneus in a dynamic fashion provided excellent outcomes.

Do peak torque angles of muscles change following anterior cruciate ligament reconstruction using hamstring or patellar tendon graft?

OBJECTIVES: This study aims to compare the effects of anterior cruciate ligament (ACL) reconstruction using autogenous hamstring or patellar tendon graft on the peak torque angle. PATIENTS AND METHODS: The study included 132 patients (103 males, 29 females; mean age 29±9 year) who were performed ACL reconstruction with autogenous hamstring or patellar tendon graft. The peak torque angles in the quadriceps and hamstring muscles were recorded using an isokinetic dynamometer. RESULTS: Angle of peak knee flexion torque occurred significantly earlier within the range of motion on the operated side than nonoperated side at 180°/second in the hamstring tendon group. Angle of peak knee extension torque occurred significantly earlier within the range of motion on the operated side than nonoperated side at 180°/second in the patellar tendon group. There were no statistically significant differences in the flexion and extension peak torque angles between the operated and nonoperated knees at 60°/second in both groups. CONCLUSION: The angle of peak torque at relatively high angular velocities is affected after ACL reconstruction in patients with hamstring or patellar tendon grafts. The graft donor site directly influences this parameter. This finding may be important for clinicians in terms of preventing re-injury.

Evaluation of plantar pressure distributions in patients with anteriorcruciate ligament deficiency: preoperative and postoperative changes.

BACKGROUND/AIM: Anterior cruciate ligament (ACL) deficiency results in several kinematic changes in the lower extremities. The aim of this study is to define the plantar pressure parameters in ACL-deficient patients and to show the effect of ACL reconstruction on dynamic plantar pressure. MATERIALS AND METHODS: Forty patients with unilateral ACL rupture and 40 healthy controls were included in this study. Dynamic plantar pressures of both groups were recorded by the EMED SF-2 system during level walking. Thirteen of the patients who had ACL reconstructions with hamstring autografts (HS group) were reevaluated at an average of 14.5 months following the ACL reconstructions. RESULTS: ACL-deficient patients had significantly lower hindfoot (P = 0.007) but higher midfoot pressure values (P = 0.03) on their ipsilateral foot compared to control group subjects. Ipsilateral hindfoot pressures were also found to be significantly lower than those of the contralateral foot (P = 0.001). Hindfoot pressure values of the HS group were increased in postoperative measurements (P = 0.01). CONCLUSION: ACL-deficient patients have altered plantar pressure distributions and ACL reconstructions restore these changes to normal. Pedobarography might be used as a practical method for dynamic functional assessment of ACL-deficient patients.

Total patellectomy for patellar aneurysmal bone cyst.

Herein we report a case of patellar aneurysmal bone cyst of a 32-year-old female patient who was admitted to our outpatient clinic due to the swelling on her left knee. She was describing no trauma history but increasing pain and that the mass was expanding gradually by the time. Although it occurs rarely in patella, evaluation by radiographic and magnetic resonance images revealed that the mass was due to the patellar aneurysmal bone cyst, which also destructed the surface of the joint. Although there was no impairment in the range of motion of the patient's left knee in the preoperative evaluation, because of the destruction, we performed total patellectomy and extensor mechanism reconstruction by Zaricznyj technique instead of curettage and grafting. The patient was satisfied with the procedure performed after the surgery and there was no complication in the follow-up.

Achilles Tendon Open Repair Augmented With Distal Turndown Tendon Flap and Posterior Crural Fasciotomy.

The aim of the present study was to investigate the outcomes after open repair of Achilles tendon rupture augmented with a distal turndown gastrocnemius flap and deep posterior crural fasciotomy based on the modified Lindholm technique. Twenty-three patients with acute Achilles tendon injury underwent open end-to-end tendon repair augmented with a distal turndown gastrocnemius flap and deep posterior compartment fasciotomy. The concentric and eccentric muscle strength was measured using a functional squat system, and dynamic balance was assessed using the Y-balance test with anterior, posteromedial, and posterolateral reach distances. Jump performance was assessed using the vertical jump and 1-leg hop tests. All patients returned to their preinjury activity level, and their mean American Orthopaedic Foot and Ankle Society hindfoot scale score was 98.2 ± 2.3 after surgery. No significant difference was found between the involved and uninvolved extremities in terms of concentric and eccentric muscle strength (p = .82 and p = .53, respectively). In addition, no significant differences were seen between legs in the vertical jump (p = .16), one-leg hop (p = .15), and balance (p > .05) tests. Open end-to-end repair of the Achilles tendon rupture with augmentation and fasciotomy of the deep posterior compartment healed without any major complications. Functional performance of the involved leg after recovery was similar to that of the uninvolved leg. The modified Lindholm surgical technique described in our report appears to be a useful intervention for acute Achilles tendon rupture.

External supports improve knee performance in anterior cruciate ligament reconstructed individuals with higher kinesiophobia levels.

BACKGROUND: The objectives of this study were to investigate the effects of knee brace (KB) and kinesiotaping (KT) on functional performance and self-reported function in individuals six months post-ACLR who desired to return to their pre-injury activity levels but felt unable to do so due to kinesiophobia. METHODS: This was a cross-sectional study involving 30 individuals six months post-ACLR with Tampa Kinesiophobia Scores >37. Individuals were tested under three conditions: no intervention, KB and KT in a randomized order. Isokinetic concentric quadriceps and hamstring strength tests, one leg hop test, star excursion balance test and global rating scale were assessed under the three conditions. RESULTS: The involved side showed that KT and KB significantly increased the hop distance (P=0.01, P=0.04) and improved balance (P=0.01, P=0.04), respectively, but only KB was found to increase the quadriceps and hamstring peak torques compared to no intervention (P<0.05). Individuals reported having better knee function with KB when compared to no intervention (P<0.001) and KT (P=0.03). CONCLUSIONS: Both KB and KT have positive effects in individuals post-ACLR which may assist in reducing kinesiophobia when returning to their pre-injury activity levels, with the KB appearing to offer the participants better knee function compared to KT.

Quadriceps and Hamstring Strength Recovery During Early Neuromuscular Rehabilitation After ACL Hamstring-Tendon Autograft Reconstruction.

CONTEXT: There is lack of information related to quadriceps and hamstring strength recovery during the early period of rehabilitation after anterior cruciate ligament reconstruction (ACLR) using hamstring-tendon graft (HTG). OBJECTIVE: To investigate quadriceps and hamstring isometric strength at 4-, 8-, and 12-wk time points after ACLR and to document the strength changes of these muscles over time. DESIGN: Longitudinal study. PARTICIPANTS: 24 patients (age 28.1 ± 8.1 y) who underwent unilateral single-bundle anatomic ACLR with 4-strand semitendinosus and gracilis tendon graft. MAIN OUTCOME MEASURES: The isometric strength of quadriceps and hamstring muscles was measured on an isokinetic dynamometer at a 60° knee-flexion angle 4, 8, and 12 wk after surgery. RESULTS: Quadriceps and hamstring strength significantly increased over time for both the involved limb (quadriceps F2,46 = 58.3, P < .001; hamstring F2,46 = 35.7, P < .001) and uninvolved limb (quadriceps F2,46 = 17.9, P < .001; hamstring F2,46 =56.9, P = .001). Quadriceps and hamstring indexes significantly changed from 4 wk (QI 57.9, HI 54.4) to 8 wk (QI 78.8, HI 69.9) and from 8 wk to 12 wk (QI 82, HI 75.7) (P < .001); however, there was no difference between indexes at the 12-wk time point (P = .17). CONCLUSIONS: The results of this study serve as a reference for clinicians while directing a rehabilitation protocol for HTG ACLR patients to better appreciate expected strength changes of the muscles in the early phase of recovery.