Journal of Experimental Orthopaedics最新文献

Purpose: Revision knee arthroplasty (rKA) is performed when a primary implant fails and is associated with a higher perioperative risk than primary arthroplasty. Early postoperative mortality after rKA in Sweden is poorly described. We aimed to estimate all-cause mortality within 90 days after rKA in Sweden and to explore associations with patient characteristics and calendar year.

Methods: Register-based cohort study using data from the Swedish Perioperative Register (SPOR). All adults undergoing rKA (national classification of surgical procedures and the kod for knee revision atrhroplasty) during 2017-2022 were included (n = 2616). The primary outcome was all-cause mortality within 90 days. Group comparisons used χ ² tests and analysis of variance; multivariable logistic regression adjusted for calendar year, sex, age group, American Society of Anaesthesiologists (ASA) category and indication for revision.

Results: Overall, 90-day mortality was low (15/2616; 0.57%; 95% confidence interval [CI]: 0.34-0.92) with no significant variation by calendar year (p = 0.100). Thirty-day mortality was 0.23% (6/2616; 95% CI: 0.10-0.47). In unadjusted analyses, age >80 years and ASA Class III/IV were associated with higher odds of 90-day mortality; in adjusted analyses, age >80 years remained the only statistically significant predictor (adjusted odds ratio [OR] 13.63; 95% CI: 3.97-46.77). Sex, ASA class and indication were not statistically significant in the adjusted model. Age, ASA class and indication showed substantial interaction in relation to 90-day mortality.

Conclusions: Ninety-day mortality after rKA in Sweden was low and remained stable between 2017 and 2022. Advanced age, higher ASA class and revision due to periprosthetic joint infection appeared to be the dominant risk factors. Preoperative preparation, medical optimization and, where feasible, prehabilitation of older and frail patients should be considered.

Level of evidence: Not applicable, quality register-based study.

Purpose: To quantitatively assess relative arterial contributions to the patellar tendon (PT) across predefined anatomic regions with 7-Tesla quantitative magnetic resonance imaging (7T-qMRI), algorithm-based histological analysis and high-resolution computed tomography (micro-CT) in a cadaveric model.

Methods: Seven fresh-frozen human cadaveric knee pairs (mean age 41.9 ± 15.5 years) underwent limited vascular dissection and arterial cannulation. Pre- and post-contrast 7T-qMRI, with a volumetric interpolated breath-hold examination (VIBE) three-dimensional T1-weighted gradient echo pulse sequence, quantified tendonous vascularity by measuring contrast enhancement. Subsequent quantitative algorithm-based histologic analysis with hematoxylin and eosin (H&E) staining followed, and two additional specimens underwent high-resolution (98 μm) micro-CT for qualitative vascular assessment.

Results: In the transverse analysis, 7T-qMRI demonstrated the highest mean relative arterial contributions in the medial region (42.4%) compared with the middle region (30.2%; p = 0.035) and higher, though not significant, than the lateral region (32.0%). The central PT demonstrated greater relative arterial contributions (37.5%) than the proximal (26.5%) or distal (29.3%) thirds (p > 0.05) in the longitudinal analysis. At the patellar enthesis, the middle third exhibited higher contributions (35.3%) than medial (28.8%) or lateral (29.6%), without significance, while the tibial tuberosity showed greater contributions along the lateral region (37.2%; p > 0.05). Histology confirmed significantly greater medial arterial contribution, with 8.3% higher supply than lateral (p = 0.018). Micro-CT revealed a robust vascular network along the medial PT with smaller branches laterally. Distal to the inferior patellar pole, a peripatellar circular network, extending medially into the posterior PT layers, was qualitatively identified.

Conclusion: 7T-qMRI and histological analyses demonstrated significantly greater arterial supply along the medial border of the PT, while micro-CT revealed a medial and peripatellar circular vascular network extending from the medial margin and the inferior patellar pole into the posterior tendon layers. These findings identify the medial margin as the main vascular source for the PT, with implications for surgical preservation and reducing PT devascularization risk.

Level of evidence: N/A.

Purpose: Unicompartmental knee arthroplasty (UKA) effectively alleviates pain and restores function in end-stage knee osteoarthritis. However, the relationship between post-operative knee skin temperature and systemic inflammatory responses remains poorly characterized. This study aimed to: (1) quantify changes in knee skin temperature and temperature difference for 6 months post-UKA, (2) analyze correlations between temperature difference and serum inflammatory markers, (3) determine whether prolonged thermal alterations represent a normal healing response or potential early warning sign of complications.

Methods: This study included 100 individuals who underwent UKA for primary osteoarthritis. Bilateral Knee skin temperatures were measured via infrared thermography preoperatively and at post-operative days (PODs) 1, 3, 5 and months 1, 3, 6, with strict ambient temperature control (20 ± 1.0°C). Concurrently, erythrocyte sedimentation rate (ESR), white blood cell count (WBC) and serum C-reactive protein (CRP) were assessed. Functional recovery was quantified using Hospital for Special Surgery (HSS) knee score.

Results: A total of 100 patients participated in the study. Bilateral knee skin temperature and temperature difference peaked at POD 3 following UKA, with gradual normalization occurring over 6 months. The patient's CRP and WBC demonstrated progressive elevation until POD 3, while ESR exhibited delayed onset of increase. Subsequent measurements showed divergence in marker resolution: CRP and WBC levels initiate decline by POD 5, whereas ESR peaked at POD 5 following UKA. All inflammatory markers returned to preoperative levels during follow-up.

Conclusion: The skin temperature of the operated knee showed a rapid increase on the first POD following UKA, peaked on POD 3, and gradually returned to normal levels by 6 months after UKA. Moreover, there is a significant correlation between changes in temperature difference and serum inflammatory markers. Normal surgical reaction may cause this alteration.

Level of evidence: Level III.

Purpose: To evaluate the influence of knee rotation angle (KRA) on tibial tubercle-trochlear groove (TT-TG) distance measured by computed tomography (CT) in female anterior knee pain (AKP) patients. To assess how correcting for knee rotation affects TT-TG values. To correlate rotational corrected TT-TG with the tibial tubercle-posterior cruciate ligament (TT-PCL) distance and tibial tubercle lateralisation (TTL) ratio.

Methods: A retrospective study was performed on 100 consecutive female AKP patients (183 lower limbs) who underwent torsional CT scans. TT-TG distance was measured and KRA was determined. Rotational-corrected TT-TG (RC TT-TG) values were calculated by neutralising knee rotation. Moreover, TT-PCL distance and TTL were measured. Two orthopaedic surgeons independently performed all measurements. Spearman correlation and linear regression analyses were used to evaluate the relationship between KRA and TT-TG changes.

Results: The mean native TT-TG was 17.22 ± 4.20 mm, mean KRA was 8.81 ± 5.08° and mean corrected TT-TG was 9.34 ± 4.70 mm. The difference between noncorrected and corrected TT-TG distance showed a very strong positive correlation with KRA (ρ = 0.934, p < 0.001). Linear regression analysis demonstrated that KRA explained 73.3% of the variability in TT-TG changes (R² = 0.733), with TT-TG decreasing by approximately 0.84 mm for each degree of knee rotation. TT-TG distance showed a moderate positive correlation with TT-PCL (ρ = 0.515, p < 0.001). In contrast, rotational-corrected (RC) TT-TG demonstrated a stronger correlation with TT-PCL (ρ = 0.644, p < 0.001). The Spearman correlations show a moderate positive association between the normal TT-TG and TTL (ρ = 0.451, p < 0.001), while the RC TT-TG exhibits a stronger correlation with TTL (ρ = 0.539, p < 0.001).

Conclusion: Knee rotation is a significant factor affecting TT-TG measurement. Measuring TT-TG after correcting knee rotation to neutral provides a more accurate estimation of this measurement. RC TT-TG correlates more closely with rotation-independent tibial-based measurements.

Level of evidence: Level IV.

Purpose: Residual rotational instability persists in 15%-30% of patients after anterior cruciate ligament (ACL) reconstruction and is associated with subjective instability, reduced return-to-sport rates and increased graft failure risk. Accurate preoperative prediction of residual pivot-shift could improve surgical planning and guide selective anterolateral reinforcement. This study aimed to develop and validate a machine-learning model to predict postoperative rotational instability (pivot-shift ≥2) using routinely available clinical and magnetic resonance imaging (MRI)-derived variables.

Methods: A multicenter retrospective cohort of patients undergoing primary ACL reconstruction was screened (n = 312), of whom 246 met inclusion criteria and were analysed, including 79 patients with postoperative pivot-shift ≥2. Variables included demographic factors, clinical laxity, posterior tibial slope, lateral meniscal extrusion, graft type and anterolateral reinforcement. Three algorithms-Random Forest, extreme gradient boosting (XGBoost) and least absolute shrinkage and selection operator (LASSO) logistic regression-were trained (70%) and internally validated (30%) using five-fold cross-validation. Model performance was evaluated using area under the receiver operating characteristic curve (AUC), calibration and decision-curve analysis. External validation was performed in an independent cohort (n = 60).

Results: XGBoost showed the best discriminative performance (AUC 0.87; sensitivity 0.83; specificity 0.79), with consistent results in external validation (AUC 0.84). Posterior tibial slope and lateral meniscal extrusion were the strongest predictors. Decision-curve analysis demonstrated superior net clinical benefit compared with rule-based approaches using International Knee Documentation Committee (IKDC) or Lachman thresholds.

Conclusions: A machine-learning model based on routine preoperative clinical and MRI variables accurately predicts residual mechanical pivot-shift after ACL reconstruction. This tool may support individualized surgical planning and selective indications for anterolateral reinforcement. Prospective preoperative evaluation of its impact on clinical decision-making is warranted.

Level of evidence: Level II, retrospective diagnostic-predictive study.

Purpose: To compare post-operative laxity and clinical outcomes following combined anterior cruciate ligament (ACL) and anterolateral ligament (ALL) reconstruction with hamstring grafts using a 1-strand versus 2-strand back-and-forth technique.

Methods: The authors retrospectively assessed a consecutive series of 348 patients (348 knees), that underwent combined ACL and ALL reconstruction using the 2-strand technique, and 130 patients (130 knees), that underwent combined ACL and ALL reconstruction using 1-strand technique between January 2020 and December 2022. Propensity score matching was performed to establish two comparable study cohorts. Patients underwent pre- and postoperative assessment by one observer using Knee injury and Osteoarthritis Outcome Score (KOOS-12), Lysholm, Tegner, and ACL-RSI scores. Physical examinations included a jerk test, and the attribution of a Lachman grade. Postoperatively, patients were assessed using the Dyneelax arthrometer on both knees to measure the differential laxity in anterior translation (AT) and internal rotation (IR).

Results: Propensity score matching resulted in 70 patients in the 2-strand group, and 70 patients in 1-strand group. Post-operatively, 18 patients were lost to follow up, and five patients underwent revision surgery due to a retear. This left a final cohort of 58 patients in the 2-strand group, aged 30.5 ± 8.1 (range, 18-52), with a BMI of 25.8 ± 4.3 (range, 20-37.8), and 59 patients in the 1-strand group, aged 30.7 ± 10.7 (range, 15-55), with a BMI of 26.5 ± 3.9 (range 16.9-38.6). At a mean follow-up of 2.4 ± 0.4 years, there were no significant differences between the groups in terms of differential laxity in AT, IR, KOOS-12, ACL-RSI, Lysholm, Tegner scores, and retear rates.

Conclusion: There was no significant difference between the 1- and 2-strand techniques for combined ACL and ALL reconstruction in terms of post-operative laxity, functional and clinical outcomes, including return to sport and Tegner activity level, suggesting that both techniques are equally effective in restoring knee stability and function.

Level of evidence: Level IV, case series.

Purpose: Complete proximal hamstring avulsion injuries are anatomically complex because of their proximity to the sciatic nerve. This study characterises neurological abnormalities following injury and surgical repair. Although denervation has been described, its severity, pattern and diagnostic thresholds in relation to magnetic resonance imaging (MRI) findings, anatomical innervation and tendon retraction distance remain poorly defined.

Methods: In this prospective longitudinal cohort study, 18 patients undergoing surgical repair of MRI-confirmed complete proximal hamstring avulsion were evaluated using serial electromyography (EMG) and MRI performed preoperatively and postoperatively over 12 months. Tendon retraction distance, muscle and sciatic nerve MRI characteristics and EMG evidence of denervation were recorded. EMG findings were used to distinguish traumatic from postoperative nerve injury. Receiver operating characteristic analysis and Youden's J-statistic were applied to determine a tendon retraction threshold associated with neurotrauma.

Results: Among the 18 patients, 5 (28%) had preoperative nerve injuries. Of the 13 patients without denervation preoperatively, 3 (23%) experienced iatrogenic injuries postsurgery. SHORE scores and MRI did not differ significantly between normal and abnormal EMG cohorts, although neurological symptoms were numerically more frequent in the abnormal group. Increased tendon retraction was significantly associated with more severe EMG abnormalities in the hamstring muscles, with a 5-cm threshold demonstrating good discrimination.

Conclusion: Proximal hamstring avulsion injuries exhibit varying degrees of neuropathology and recovery. MRI-measured retraction, not MRI signal changes, may predict neurotrauma. EMG is required to confirm denervation. Retraction distance over > 5 cm (nerve at risk distance, NARD) is associated with a substantially increased risk of neurotrauma, but the long-term clinical consequences of underlying nerve injury, especially in the athlete, require further investigation.

Level of evidence: Level II, prospective longitudinal cohort study.

Purpose: (1) To explore postoperative factors associated with effusion after anterior cruciate ligament reconstruction (ACLR), and (2) to investigate the associations between effusion and quadriceps tension and activation across rehabilitation and return-to-sport (RTS) phases.

Methods: In this cross-sectional study, participants were assessed at approximately 3, 6, 12 and ~24 months post-ACLR and further analysed by phase (3-6 vs. 12-24 months). Effusion (Anterior Cruciate Ligament Osteoarthritis Score [ACLOAS]) and patellar alignment (Insall-Salvati ratio [ISR], bisect offset [BO], patellar tilt angle [PTA]) were quantified by 3.0-T magnetic resonance imaging. Quadriceps tension and activation were quantified by shear wave elastography (SWE) and surface electromyography (EMG) during resting and isometric knee extension conditions. Physical activity was assessed using The International Physical Activity Questionnaire-Short Form (IPAQ-SF). Ordinal logistic regression tested associations with effusion; generalised linear models evaluated relationships between effusion and muscle outcomes (α = 0.05).

Results: A total of 119 participants (75% male, age 29 ± 6 years) who underwent single-bundle ACLR with hamstring tendon autograft were included in this study. Higher postoperative physical activity (MET-min/week) was associated with higher effusion grade at 3-month (odds ratio [OR] = 1.07, p < 0.01) and 24-month (OR = 1.05, p = 0.05) groups; greater ISR was associated with higher effusion grade at ≥12 months (OR = 1.08, p < 0.01). Higher effusion grade was associated with higher vastus medialis and lateralis shear modulus at ≥12 months (B = 7-11 kPa, all p < 0.04) during the isometric knee extension condition; No association was observed for normalised EMG activation (all p > 0.09).

Conclusions: Postoperative activity and patella alta were associated with joint effusion after ACLR. Additionally, residual effusion was associated with higher quadriceps tension under submaximal contraction beyond 1 year. These findings suggest that phase-specific monitoring of physical activity and patellofemoral joint loading may benefit joint health and knee function after ACLR.

Level of evidence: Level IV.

The integration of artificial intelligence (AI) into orthopaedic practice is no longer a theoretical future but an inevitable reality. As AI models increasingly demonstrate superior performance in specific diagnostic and administrative tasks, concerns have arisen regarding the potential replacement of physicians and the erosion of clinical competency. This narrative review synthesizes current evidence to reframe the debate from a fear of replacement to a strategy of augmentation. Pathways leading to 'deskilling'-the loss of existing expertise-and the emerging threat of 'never-skilling', where trainees fail to acquire foundational proficiencies due to premature reliance on automation, are analysed. Current AI applications function primarily as assistants rather than autonomous agents, offering an opportunity for 'upskilling' by liberating clinicians from repetitive administrative burdens and standardizing diagnostic accuracy. However, realizing this benefit requires deliberate educational mechanisms; one has to argue that maintaining clinical excellence requires a shift in training paradigms, emphasizing critical oversight where human reasoning validates AI outputs. AI will not replace the orthopaedic surgeon in the foreseeable future; rather, it will necessitate an evolution of the physician's role. By automating routine tasks, AI allows the modern physician to operate at a higher level, focusing on complex decision-making, procedural excellence and patient empathy. The future requires mechanisms to ensure AI remains a tool for professional elevation rather than a catalyst for skill degradation.

Level of evidence: Level V.

Purpose: The purpose of this study was to compare preservation of posterior condylar offset (PCO) and posterior condylar offset ratio (PCOR) after medial pivot (MP) total knee arthroplasty (TKA) performed with kinematic (KA) or mechanical alignment (MA), and to assess whether changes in these parameters associate with 2-year clinical outcomes.

Methods: This post hoc radiographic analysis of a prospective randomised trial included 200 patients (100 KA, 100 MA). PCO and PCOR were measured on standardised pre and postoperative lateral radiographs. Postoperative values were compared between groups using analysis of covariance, adjusting for preoperative measurements. Associations between changes in PCO/PCOR and 2-year patient-reported outcome measures (PROMs) and range of motion (ROM) were assessed in a subset of 100 patients using multivariable models.

Results: Two hundred patients were included radiographically (MA 100, KA 100; mean age 68.9 ± 9.2 years). Adjusted between-group differences were 1.23 mm for postoperative PCO (90% confidence interval [CI]: -0.10 to 2.56; p = 0.13) and 0.023 for postoperative PCOR (90% CI 0.003 to 0.043; p = 0.06). Equivalence within ± 2.0 mm (PCO) and ± 0.02 (PCOR) was not demonstrated. Change-score analyses were concordant (ΔPCO difference 1.02 mm; 90% CI: -0.50 to 2.54; p = 0.27; ΔPCOR difference 0.026; 90% CI: -0.012 to 0.064; p = 0.26). In 100 patients with complete paired radiographic and 2-year clinical data, ΔPCO/ΔPCOR showed no significant associations with PROMs or ROM after adjustment. Interobserver reliability was excellent (intraclass correlation coefficient [ICC] 0.93 for PCO; 0.89 for PCOR).

Conclusion: In MP TKA, KA and MA did not differ significantly in preserving PCO or PCOR; however, statistical equivalence within prespecified margins was not established. Changes in PCO/PCOR were not associated with 2‑year outcomes, suggesting that precise surgical execution, including specific rotational strategies, rather than alignment philosophy alone, is key to maintaining posterior femoral geometry in this implant design.

Level of evidence: Level III, post hoc analysis of data from a randomised controlled trial.