Sanjay Kumar Sureen1*, Dialdeen Mohamed Youssef2, Hassan Yousuf Bilal3

¹Surgeon, Department of Orthopedics, Prime Hospital, Dubai, UAE

²Consultant, Department of Orthopedics, Prime Hospital, Dubai, UAE

³Registrar, Department of Orthopedics, Prime Hospital, Dubai, UAE

^* Corresponding Author: Sanjay Kumar Sureen, Surgeon, Department of Orthopedics, Prime Hospital, Dubai, UAE.

Received: 10 February 2026; Accepted: 17 February 2026; Published: 24 February 2026

Article Information

Citation: Sanjay Kumar Sureen, Dialdeen Mohamed Youssef, Hassan Yousuf Bilal. Predictors of Functional Recovery After ACL Reconstruction in Mid-Teen Patients: An Analysis of Clinical and Rehabilitation Factors. Journal of Orthopedics and Sports Medicine. 8 (2026): 39-48.

DOI: 10.26502/josm.511500252

Abstract

Keywords

ALC reconstruction; Mid-Teen patients; Functional recovery; Rehabilitation adherence; Supervised physiotherapy; Return to sport

Article Details

1. Introduction

Anterior cruciate ligament (ACL) rupture in adolescents has become an increasingly common sports-related injury, paralleling earlier sport specialization, higher training loads, and greater exposure to pivoting and landing tasks. Contemporary registry and population data from high-income settings show a clear upward trajectory in ACL reconstruction among younger age groups, with particular concentration in late adolescence when sport participation intensity often peaks [1,2]. Although epidemiology varies across regions, recent pediatric and adolescent data from Asia also indicate substantial cruciate ligament injury burden and frequent concomitant meniscal pathology, underscoring that this is not a purely Western problem [3].

ACL reconstruction is widely performed in mid-teen patients to restore functional stability, facilitate safe return to sport, and reduce secondary meniscal or chondral damage associated with recurrent giving-way episodes. Yet “success” after surgery is not uniform, and the adolescent profile is distinct: high performance demands, variable neuromuscular control during growth, and fluctuating psychosocial readiness can all influence recovery trajectories. Return-to-sport outcomes illustrate this tension; pooled analyses in children and adolescents suggest high rates of return to any sport, but clinically meaningful risks of graft rupture and contralateral ACL injury persist, particularly after resumption of high-risk activities [4,5].

Functional recovery is increasingly framed as a multidimensional endpoint that combines patient-reported outcomes with objective performance symmetry, strength restoration, symptom control, and effusion or motion status. Patient-reported instruments such as the IKDC family, including pediatric adaptations, remain central because they capture symptoms and perceived function that may diverge from laboratory or field tests [6]. However, even when athletes are “cleared” clinically, objective deficits often remain; prospective cohort work in young athletes has shown that only a small fraction meet combined cutoffs for subjective score, strength limb symmetry, and hop performance at return-to-sport clearance [7]. This disconnect likely contributes to the elevated reinjury rates observed in younger populations and supports a more criterion-based interpretation of recovery rather than relying on time alone [5,7].

Both clinical severity and care pathways before surgery can shape post-operative potential. Delay from injury to reconstruction has been associated with higher rates of meniscal tears in pediatric patients, plausibly through ongoing instability episodes and cumulative intra-articular insult [8]. Concomitant cartilage injury and meniscal procedures may further complicate rehabilitation due to pain, swelling, modified loading, and altered confidence in the knee. At the same time, rehabilitation exposure is not simply a background variable; it is a dose-dependent intervention. Earlier initiation of structured rehabilitation, adequate supervised physiotherapy, and adherence to progressive home programs are consistently emphasized as key determinants of strength symmetry, hop performance, and sport-specific capacity, which are themselves central to the modern definition of functional recovery [7,9].

Psychological readiness is another adolescent-sensitive dimension. Lower readiness to return to sport has been linked with higher risk of subsequent ACL injury, and adolescent-specific analyses highlight that confidence, fear, and perceived knee trustworthiness can lag behind physical milestones or, conversely, outpace them in ways that encourage premature exposure [10,11]. Meanwhile, the broader literature continues to show that determinants of return to sport are multifactorial and heterogeneous, spanning contextual, surgical, physical, and psychological domains, with substantial variability in outcome definitions between studies [12,13].

Despite this, important gaps remain. Many adolescent studies report overall outcomes or reinjury rates without integrating measurable rehabilitation dose, milestone achievement, and pre-operative clinical status into a single explanatory framework. Evidence is also dominated by well-resourced systems with mature registries; in many low- and middle-income contexts, delays to surgery, access to supervised physiotherapy, and adherence constraints may differ materially, and locally grounded predictor models are limited. Against this backdrop, identifying practical, modifiable predictors of recovery is clinically valuable because it can guide risk stratification, target rehabilitation resources, and improve shared decision-making around return to sport. Accordingly, this study aims to determine predictors of functional recovery at 12 months after primary ACL reconstruction in mid-teen patients.

2. Methodology and Materials

This observational, analytical study was conducted among mid-teen patients undergoing primary ACL reconstruction at the Department of Orthopedic Surgery, Prime Hospital, Dubai, UAE, with prospective follow-up where feasible. During two years from January 2024 to December 2025, a total of 350 cases were enrolled in this study. Eligible participants were boys and girls within the predefined mid-teenage range who received primary ACL reconstruction for a unilateral ACL tear, and who were complete functional testing and patient-reported outcome measures. Exclusion criteria included revision ACL reconstruction, multi-ligament knee injuries requiring staged reconstruction, major fractures around the knee, neuromuscular disorders affecting gait, and insufficient follow-up data at the primary endpoint.

Baseline data was recorded preoperatively using a structured case record form: sociodemographic, sport type and level, injury mechanism, time from injury to surgery, clinical status including pain score, effusion, and range of motion, and MRI-confirmed associated injuries such as meniscal tears, cartilage lesions, and collateral ligament injury. Intraoperative variables were including graft type and diameter, fixation method, tunnel technique, meniscal or cartilage procedures, operative time, and early complications. Rehabilitation exposure was captured as measurable dose and quality indicators: time to start rehabilitation, supervised physiotherapy attendance, adherence category, home program use, brace and crutch duration, and achievement of key milestones such as full extension by 2 weeks and flexion ≥120 degrees by 6 weeks.

Participants were assessed at standard intervals, for example, 6 weeks, 3 months, 6 months, 9 months, and 12 months. The primary outcome was functional recovery at 12 months, operationalized either as a continuous score using Pedi IKDC or IKDC, or as a binary recovered status defined by a composite of symptom score threshold plus objective symmetry, for example, hop test limb symmetry index ≥90%, full ROM, and absence of clinically relevant effusion. Secondary outcomes were including return to sport status and timing, psychological readiness if ACL RSI is used, and re-injury or re-operation events.

Data was analyzed using descriptive statistics (SPSS, V-26.0), then bivariate comparisons between recovered and not recovered groups using chi-square or Fisher’s exact tests for categorical variables, and t-test or Mann-Whitney U tests for continuous variables. Independent predictors were evaluated using multivariable logistic regression for binary recovery, or linear regression for continuous outcomes, with assessment of multicollinearity, model fit, and discrimination where applicable; missing data was handled using predefined rules, with sensitivity analyses if needed. Ethical approval was obtained, with assent from participants and consent from guardians, and confidentiality maintained through de-identified study IDs.

3. Results

Among 350 mid-teen ACL reconstruction patients, 216 (61.7%) achieved functional recovery by 12 months. Mean age was similar between groups (15.3±1.2 vs 15.1±1.3 years; p=0.18). Recovery was more frequent in males (68.5% vs 56.7%; p=0.025). The recovered group had a significantly lower BMI (23.6±3.8 vs 25.0±4.5 kg/m²; p=0.002) and higher baseline activity on the Tegner scale (6.4±1.3 vs 5.9±1.4; p=0.001). Pre-injury sports participation was also higher among recovered patients (90.7% vs 82.1%; p=0.017), and sports level differed, with relatively fewer recreational athletes in the recovered group (32.7% vs 43.6%; overall p=0.031). Dominant leg and side of the injured knee were comparable (p>0.70) (Table 1).

Table 1: Baseline sociodemographic and pre injury characteristics (N = 350).

Not recovered patients more often developed acute swelling within 24 hours (72.4% vs 59.3%; p=0.014) and had longer delays from injury to surgery (median 104 days, IQR 70-160 vs 72 days, IQR 45-110; p=0.001). Instability burden was higher in the not recovered group, with ≥3 giving-way episodes in 44.8% vs 21.3%, while zero episodes were more common among recovered (42.6% vs 20.9%; p<0.001). Pre-op physiotherapy was more frequent in recovered patients (44.0% vs 29.9%; p=0.008). Clinically, recovered patients had better pre-op status, including less extension loss (2.1±2.7 vs 3.4±3.1 degrees; p<0.001), greater flexion (128±11 vs 123±14 degrees; p<0.001), less effusion (none: 39.8% vs 23.9%; p<0.001), and lower pain (VAS 3.2±1.5 vs 4.1±1.7; p<0.001). On MRI, meniscal tears were less frequent overall in recovered patients (none: 41.2% vs 30.6%; p=0.041), cartilage injury severity was lower (no cartilage injury: 62.0% vs 49.3%; p=0.019), and MCL injury was less common (15.7% vs 23.9%; p=0.045), while bone bruise rates did not differ significantly (p=0.17) (Table 2).

Table 2: Injury profile, pre operative clinical status, and MRI findings (N = 350).

Most procedures were single-bundle reconstructions in both groups (88.0% vs 85.1%; p=0.46), and graft type distribution was similar (hamstring autograft about 71% in each; p=0.8). However, recovered patients had a slightly larger mean graft diameter (8.3±0.6 vs 8.1±0.7 mm; p=0.006). Fixation choices and tunnel drilling approach were comparable (p>0.10). Meniscus procedures differed: recovered patients more often had no meniscal procedure (48.6% vs 35.8%), whereas repairs were more common in the non-recovered group (43.3% vs 34.3%; p=0.021). Operative time was shorter among recovered patients (92±24 vs 101±29 minutes; p=0.002), while tourniquet time and immediate intra-op complications were not significantly different (Table 3).

Table 3: Intra operative and surgical characteristics (N = 350).

Rehabilitation variables showed the strongest contrasts. Starting rehab within 1 week was much more common in recovered patients (55.1% vs 29.9%), while delayed start beyond 2 weeks was more frequent in non-recovered patients (29.9% vs 11.6%; p<0.001). Supervised physiotherapy attendance was higher in the recovered group (81.9% vs 58.2%; p<0.001), and dose-response was evident: >20 supervised sessions occurred in 31.9% of recovered vs 9.0% of not recovered, whereas zero sessions were far more common among not recovered (41.8% vs 18.1%; p<0.001). Home exercise programs were widely prescribed but still slightly higher in recovered (95.4% vs 91.0%; p=0.028). Self-reported adherence strongly separated groups: poor adherence was 8.3% in recovered versus 35.8% in not recovered, while excellent adherence was 34.7% versus 9.0% (p<0.001). Key milestones were achieved far more often in recovered patients: full extension by 2 weeks (78.2% vs 40.3%), flexion ≥120° by 6 weeks (88.0% vs 59.7%), jogging by 3 months (69.9% vs 38.1%), agility by 6 months (63.9% vs 29.9%), and sport-specific drills by 9 months (57.4% vs 23.9%), all p<0.001 (Table 4).

Table 4: Rehabilitation exposure, adherence, and milestone achievement (N = 350).

Baseline patient-reported scores were similar pre-operatively for IKDC (45.3±12.1 vs 44.6±12.8; p=0.58) and KOOS-Child Sport (38.9±15.2 vs 37.6±14.9; p=0.46). By 6 months, recovered patients had significantly better outcomes across measures, with IKDC 72.4±10.8 vs 63.2±11.6 and KOOS-Sport 70.6±14.0 vs 58.3±16.1 (both p<0.001), and these gaps widened at 12 months (IKDC 88.7±6.8 vs 73.4±9.8; KOOS-Sport 86.9±10.4 vs 67.5±15.2; both p<0.001). Objective function also favored recovered patients at 6 and 12 months: hop-test LSI (12 months 94.8±5.1 vs 84.2±8.7; p<0.001) and quadriceps strength LSI (12 months 93.6 ± 5.7 vs 82.1 ± 8.9; p<0.001). At 12 months, recovered patients reported less pain (VAS 1.1±1.0 vs 2.6±1.5; p<0.001), had less effusion (none 90.7% vs 68.66%; p<0.001), and demonstrated better ROM, with smaller extension deficit (0.3±0.8 vs 1.5±1.6 degrees; p<0.001) and greater flexion (136±6 vs 131±8 degrees; p<0.001) (Table 5).

Table 5: Functional outcomes and clinical status at follow up.

Return-to-sport outcomes were substantially better in recovered patients, including return to any sport (88.0% vs 61.9%; p<0.001), return to pre-injury sport (71.8% vs 38.1%; p<0.001), and return to the same level (60.2% vs 26.1%; p<0.001). Recovered patients also returned earlier (8.7±1.9 vs 10.2±2.3 months; p<0.001). Re-injury rates were low and similar between groups (ipsilateral graft rupture 2.3% vs 3.0%; contralateral ACL 1.9% vs 2.2%; p=0.83). However, stiffness-related complications were more frequent among non-recovered patients, including arthrofibrosis (6.7% vs 1.9%; p=0.018) and cyclops lesion treatment (8.2% vs 2.8%; p=0.02), and re-operation was higher in the non-recovered group (11.2% vs 4.2%; p=0.012) (Table 6).

Table 6: Return to sport, complications, and reinjury (by 12 months or last follow up).

After adjustment, modifiable clinical and rehabilitation factors remained the main independent predictors. Higher BMI reduced the odds of recovery (AOR 0.93 per 1 kg/m², 95% CI 0.89–0.98; p=0.004), and longer injury-to-surgery time was also unfavorable (AOR 0.89 per 30 days, 95% CI 0.80–0.98; p=0.016). Cartilage injury grade ≥2 predicted poorer recovery (AOR 0.60, 95% CI 0.37–0.97; p=0.038). In contrast, supervised physiotherapy doubled recovery odds (AOR 2.14, 95% CI 1.28–3.57; p=0.004), good-to-excellent adherence tripled it (AOR 3.21, 95% CI 1.96–5.25; p<0.001), and achieving full extension by 2 weeks was a strong early milestone predictor (AOR 2.63, 95% CI 1.63–4.25; p<0.001). Male sex showed a modest positive association (AOR 1.55, 95% CI 1.01–2.38; p=0.045), while age and meniscus repair (vs none) were not significant (Table 7).

Table 7: Multivariable logistic regression model for predictors of functional recovery (12 months).

4. Discussion

In this mid-teen cohort, functional recovery at 12 months was achieved by 61.7% (216 of 350), and the contrast between recovered and not recovered patients was clinically meaningful across symptoms, objective symmetry, and sport participation. Recovered participants demonstrated substantially higher 12-month IKDC scores (88.7±6.8 vs 73.4±9.8) and KOOS-Child Sport scores (86.9±10.4 vs 67.5±15.2), alongside higher hop and quadriceps strength limb symmetry indices, lower pain, less effusion, and smaller residual ROM deficits. These findings align with prognostic literature suggesting that early symptom resolution and restoration of strength and motion underpin patient-reported recovery, while concomitant intra-articular pathology can constrain longer-term outcomes. Studies from large cohorts and systematic reviews consistently report worse patient-reported trajectories when cartilage lesions and meniscal pathology are present, even when reconstruction is technically successful [14,15].

Several predictors in our multivariable model were modifiable rehabilitation or timing factors. Supervised physiotherapy (AOR 2.14) and good-to-excellent adherence (AOR 3.21) were among the strongest independent predictors, and they were mirrored by clear, dose-like gradients in the raw comparisons, including a markedly higher proportion completing >20 supervised sessions in the recovered group. This is highly consistent with evidence that adherence and participation are central determinants of ACL rehabilitation success, with scoping review data identifying motivation, therapeutic alliance, access, and clear goal setting as key drivers of adherence, and conversely, logistical barriers and low perceived benefit as common reasons for disengagement [16]. Clinically, our data reinforce that rehabilitation should be treated as an exposure with measurable intensity and fidelity, rather than a uniform post-surgical aftercare step.

Early milestone achievement also emerged as a decisive signal. Achieving full extension by two weeks independently increased the odds of recovery (AOR 2.63), and not recovered patients experienced higher arthrofibrosis and cyclops lesion treatment rates. This pattern is biologically plausible and strongly supported by prior work: early postoperative extension deficits increase the risk of cyclops syndrome in large registry analyses [17], and systematic review evidence links extension deficit to anterior knee pain after ACL reconstruction [18]. Together, these data support a pragmatic clinical implication for adolescent services: establish extension-focused early protocols, monitor extension objectively at each early visit, and trigger rapid escalation when extension is lagging, because early deficits are not benign and may become self-perpetuating through pain, guarding, and impaired quadriceps activation.

Timing of surgery also mattered in our cohort: the recovered group had a shorter median injury-to-surgery interval (72 vs 104 days), and each additional 30 days reduced the odds of recovery (AOR 0.89). This is directionally consistent with evidence that delaying reconstruction beyond clinically relevant thresholds reduces the likelihood of achieving clinically meaningful improvement [19], plausibly through prolonged instability, recurrent “giving way”, and accrual of secondary intra-articular injury. Delays may therefore act both directly, by prolonging symptomatic impairment and deconditioning, and indirectly, by increasing meniscal and chondral burden, which is repeatedly associated with worse patient-reported prognosis in cohort and systematic review evidence [14,15,19].

Cartilage injury grade ≥2 independently predicted poorer recovery (AOR 0.60), while meniscal repair was not an independent predictor after adjustment. Prior evidence generally indicates that cartilage lesions, and to a lesser extent meniscal injury, are associated with worse patient-reported outcomes over mid-term follow-up [14,15], and recent systematic review and meta-analytic evidence focusing on concomitant focal cartilage lesions similarly supports a poorer prognosis following surgical treatment [20]. The lack of an independent meniscal repair effect in our study may reflect confounding by indication, where larger tears and more symptomatic knees are preferentially repaired, while effective repair can also mitigate longer-term consequences; it may also reflect that our endpoint is 12 months, whereas meniscal and chondral sequelae may exert stronger separation later.

Body composition and sex effects were present but likely context-dependent. Higher BMI reduced odds of recovery (AOR 0.93 per kg/m²), which is consistent with plausible mechanical and behavioral pathways, including increased joint loading, slower strength normalization, and potentially lower rehabilitation tolerance or participation. However, published findings on BMI are mixed, and a recent study in a specific graft context reported no meaningful influence of BMI 15-30 on patient-reported outcomes after ACL surgery with a 10 mm BPTB graft [21]. These discrepancies may relate to age, graft selection, BMI range, rehabilitation delivery, and outcome definitions, emphasizing that BMI is best treated as a risk stratifier that should trigger enhanced rehabilitation support rather than as a deterministic barrier. Sex differences are also reported variably across studies, but systematic review and meta-analysis indicate that outcomes can differ by sex depending on the metric and follow-up window [22], and our male sex association may reflect differences in baseline sport exposure, rehabilitation dose, or psychosocial recovery factors not fully captured in our dataset.

Finally, our objective testing results fit contemporary concerns about how symmetry is interpreted. While recovered patients exceeded common RTS symmetry thresholds (for example, mean hop LSI 94.8% and quadriceps strength LSI 93.6% at 12 months), evidence shows that limb symmetry indices can overestimate true knee function because the contralateral limb may also decondition, and performance symmetry does not guarantee symmetric biomechanics [23,24]. Moreover, quadriceps strength may be more tightly linked to patient function than hop performance alone [25]. These insights support a practical refinement of adolescent follow-up, combine strength testing with movement quality assessment, symptom status, effusion, and ROM, rather than relying on a single LSI cut-off. Our reinjury rates were low and did not differ significantly by recovery status, but modern evidence in young athletes suggests that RTS criteria alone may not fully identify second-injury risk [26], while decision-rule frameworks that incorporate strength and timed RTS can reduce reinjury risk in prospective cohorts [27].

5. Limitations of the Study:

Key limitations include the observational design, which limits causal inference and leaves potential residual confounding, despite multivariable adjustment. Rehabilitation exposure and adherence were partly self-reported, introducing recall and social desirability bias, and rehabilitation “dose” may have varied across providers and settings. Outcomes were assessed primarily at 12 months, so longer-term function, reinjury, and degenerative changes were not captured, and some clinically relevant psychosocial factors, for example, fear of re-injury or readiness, were not measured, which may influence recovery and return to sport.

6. Conclusion

Functional recovery at 12 months after ACL reconstruction in mid-teen patients was achieved in nearly two-thirds of cases, with markedly better patient-reported and objective functional outcomes in the recovered group. Independent predictors of recovery were predominantly modifiable, including supervised physiotherapy, good-to-excellent adherence, and early restoration of full extension, while higher BMI, longer injury-to-surgery delay, and cartilage injury were associated with poorer recovery. These findings support prioritizing timely surgery, structured and adequately supervised rehabilitation, and early motion milestone monitoring to optimize adolescent ACL outcomes and return-to-sport readiness.

7. Recommendations

Implement standardized, milestone-driven rehabilitation pathways that prioritize early full extension, progressive quadriceps strengthening, and objective functional testing, with guaranteed access to supervised physiotherapy and adherence-support strategies for adolescents. Reduce injury-to-surgery delays through streamlined referral and scheduling, and stratify follow-up intensity for higher-risk patients, for example, those with higher BMI, delayed presentation, or cartilage injury, to prevent stiffness, optimize return-to-sport readiness, and minimize re-operations.

Funding:

No funding sources.

Conflict of interest:

None declared.

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