Rapid high-throughput processing of tissue samples for microbiological diagnosis of periprosthetic joint infections using bead-beating homogenization.

Enrichment of periprosthetic tissue samples in blood culture bottles (BCBs) for microbiological diagnosis of periprosthetic joint infections (PJI) is more reliable than the use of an enrichment broth. Nevertheless, the extremely time-consuming homogenization of the samples for BCB processing has so far limited its use, especially in high-throughput settings. We aimed to establish a highly scalable homogenization process of tissue samples for long-term incubation in BCBs. A protocol for homogenization of tissue samples using bead beating was established and validated. In a second step, the use of the homogenate for enrichment in BCBs was compared to the use of thioglycolate broth (TB) in terms of diagnostic accuracy using clinical tissue samples from 150 patients with suspected PJI. Among 150 analyzed samples, 35 samples met the microbiological criteria for PJI. Using BCB, 32 of 35 (91.4%) PJI were detected compared to 30 of 35 (85.7%) by TB. The use of BCB had a lower secondary contamination rate (2/115; 1.7% vs 4/115; 3.5%) but the trend was not significant due to low numbers of samples (P = 0.39). The time to process a batch of 12 samples using the established homogenization method was 23 ± 5 min (n = 10 batches). We established and validated a homogenization workflow that achieves the highest sensitivity in the microbiological diagnostic of PJI. The enrichment of the tissue homogenate in BCBs showed equally good results as the use of enrichment broth and allows semi-automated high-throughput processing while demonstrating lower contamination rates in our study.

Evidence of Bacterial Metabolism in Synovial Fluid of Patients With Graft Failure After Anterior Cruciate Ligament Reconstruction: A Microbiological Comparison of Primary Anterior Cruciate Ligament and Hamstring Tendon Autograft Ruptures.

PURPOSE: To investigate whether the bacterial presence in a primary ruptured native anterior cruciate ligament (ACL) differs from that in a ruptured hamstrings ACL autograft and whether low-grade infections cumulatively can be detected in the case of graft failure. METHODS: In a retrospective case-control study with prospectively collected data, synovial fluid aspirates and tissue samples of failed ACL grafts were examined for evidence of bacterial colonization and compared to samples of the native ACL in primary ACL reconstruction (ACLR) using microbiological culture, 16S rRNA-PCR and histopathological examination. Furthermore, synovial fluid aspiration was investigated for possible future biomarkers for a low-grade infection. RESULTS: A total of 112 consecutive patients undergoing primary ACLR without history of previous surgeries to the affected knee (n = 59) and revision ACLR after reconstruction with a hamstring tendon autograft (n = 53) were recruited from one center. No patient had a history or showed clinical signs of infection. A total of 389 samples were analyzed by culture. Bacteria were detected in 9.4% of patients with a graft rupture (n = 5/53) compared to 3.4% of patients with a primary ACL rupture (n = 2/59) showing no statistical difference (P = .192). One patient with a "true" low-grade infection was found in our study population, resulting in a prevalence of 1.9% (1/53) in the graft group. The percentage of polymorphonuclear leukocytes (PMN%) as a highly sensitive marker for joint infections was significantly higher in aspirated synovial fluid of graft ruptures (27% ± 3% vs 20% ± 4%; P = .032), as well as glucose levels were significantly lower (83 mg/dL ± 2 mg/dL vs 88 mg/dL ± 2 mg/dL; P = .042). CONCLUSIONS: Synovial fluid obtained before revision ACLR showed a higher percentage of polymorphonuclear leukocytes and lower glucose levels compared with primary ACLR, suggesting bacterial metabolism and demonstrating that the intra-articular milieu changes significantly after ACLR. Tissue samples of ACL grafts revealed a low-grade infection in one case, although overall cultivable bacterial presence did not differ significantly when compared to samples of a native ACL. LEVEL OF EVIDENCE: Level III, retrospective case-control study.

Effects of exercise prehabilitation before anterior cruciate ligament reconstruction on functional outcomes during pre- and postoperative rehabilitation - protocol for a single-blinded randomised controlled trial.

BACKGROUND: Although a benefit of preoperative training prior to anterior cruciate ligament (ACL) reconstruction is likely, there is no consensus on the optimal content (criteria-based programme), supervision (one-on-one guidance or self-administered training) and general setting of preoperative training after ACL injuries. The purpose of this trial is to investigate the efficacy of an individually adaptive, guided, structured and criteria-based preoperative rehabilitation programme in comparison to a non-guided and self-administered home training programme. METHODS: The planned single-blinded randomised controlled trial study was approved by the ethics committee of the German Sport University on June 14, 2022 (ethics application no. 093/2022) and prospectively registered (DRKS-ID: DRKS00030312; date of registration: 26.09.2022). N = 114 participants between 16 and 60 years of age with a unilateral ACL rupture and scheduled ACL reconstruction with a hamstring or quadriceps tendon autograft will be randomly (block-randomisation, 1:1 allocation) and blinded assigned to one of two groups: intervention group (structured, criteria-based, guided prehabilitation training) and comparator group (non-guided, self-administered home training). After surgical reconstruction, patients of both groups participate in the same standard, functional measurement-guided, postoperative rehabilitation programme. Stepwise increasing the functional requirements of the assessments, all participants participate in testing at the day of anamnesis (t1), 1-7 days before surgical reconstruction (t2), day of surgical reconstruction (t3) and 30 (t4), 60 (t5), 90 (t6) and 180 (t7) days post-reconstruction. The primary outcome is the overall self-reported knee condition, assessed by the sum score of all sub-scales of the Knee injury and Osteoarthritis Outcome Score (KOOS). Secondary outcomes include functional outcomes (range of motion, knee flexors and extensors and plantar flexors strength/torque, functional postural control, jumping ability), workability and return to sport (RTS) (psychological readiness, RTS success). DISCUSSION: The planned study targets to fill a gap in the evidence regarding effective designs of prehabilitation training before surgical ACL reconstruction. Potential difficulties that could affect the conduct of the study are lack of treatment adherence of the patients and high dropout. TRIAL REGISTRATION: German Register of Clinical Trials DRKS-ID: DRKS00030312 . Registered on 26 September 2022.

Semitendinosus tendons are commonly contaminated with skin flora during graft harvest for anterior cruciate ligament reconstruction.

PURPOSE: To investigate the rate of bacterial contamination of semitendinosus (ST) tendons during graft harvest in anterior cruciate ligament reconstruction (ACLR), in order to precisely specify the underlying pathogens and obtain data on their susceptibility to potential antibiotics. METHODS: In a prospective study, a total of 59 consecutive patients undergoing primary ACLR were recruited from one centre. No patient had history of previous surgery to the knee or showed clinical signs of infection. Four tissue samples of harvested ST tendons for anterior cruciate ligament (ACL) autografts (case group; ST) were examined for evidence of bacterial colonisation and compared to four tissue samples of the native ACL as negative controls (control group; ACL). Three of the respective samples were subjected to cultural microbiological examination and one to 16S rRNA-PCR. Antibiotic susceptibility testing was performed for each pathogen that was identified. RESULTS: A total of 342 samples were analysed by culture. Significantly more patients showed a positive culture of the ST (33.9%; n = 20/59) compared to 3.4% of patients (n = 2/59) with positive culturing of the ACL (p < 0.0001). Including 16S rRNA-PCR, in a total of 42.4% (25/59) of patients, bacteria were detected in at least one ST sample either by PCR and/or culture. All species found (n = 33) belong to the typical skin flora with Staphylococcus epidermidis (39.4%; n = 13/33) being the most common species, followed by Staphylococcus capitis (24.2%; n = 8/33). All tested isolates (n = 29) were susceptible to vancomycin (29/29, 100%), 69% (n = 20/29) to oxacillin and 65.5% (n = 19/29) to clindamycin. CONCLUSION: ST autografts for ACLR were commonly contaminated with skin commensal bacteria during harvest. One-third of the isolates showed resistance to typical perioperative intravenous antibiotics, whereas all isolates were sensitive to vancomycin. Therefore, routine prophylactic decontamination of all hamstring autografts before implantation should be recommended, preferably with topical vancomycin. LEVEL OF EVIDENCE: Level III.

The Association between Multidirectional Speed Performance, Dynamic Balance and Chronological Age in Young Soccer Players.

The ability to maintain a stable single-leg balance stance during a fast change of direction movement is a fundamental aspect both for improving sport-specific skills and for prevention strategies. The aim of this cross-sectional study was to investigate the associations between multidirectional speed performance (MDS), dynamic balance performance (DBP), and chronological age in young and uninjured soccer players. In addition, it was examined whether chronological age and balance can predict variance in speed performance. One-hundred forty-six young male soccer players (age range 11-19) performed the y-balance test (YBT) and the lower extremity functional test (LEFT). Descriptive statistics, Pearson correlation, and multiple regression analysis were executed. The analyses were carried out on the further variables: for the DBP, the YBT composite score % (CS dominant leg/CS non-dominant leg) and limb symmetry index % (LSI) were used; for the MDS, the LEFT time in seconds (s) was used. Findings revealed LEFT scores to have a significant association with chronological age (p = 0.000), CS dominant (p = 0.019) and LSI (p = 0.044) of the YBT. In addition, CS dominant and chronological age explained the variance of the LEFT by 44%, regardless of LSI. To conclude, MDS revealed a strong association with DBP of the dominant side but a small association with LSI. In addition, a small association was found between quick LEFT times and older players. Finally, MDS variance can be predicted from DBP of the dominant side and chronological age in young soccer players. The tests used in this study could be useful screening tools for the detection of performance deficits, the implementation of prevention training programs, and the optimization of selection strategies in soccer academies.

High variability of tibial slope measurement methods in daily clinical practice: Comparisons between measurements on lateral radiograph, magnetic resonance imaging, and computed tomography.

BACKGROUND: Tibial slope measurements are important in guiding clinical decisions in the field of orthopedic surgery. However, there are multiple techniques across different medical imaging modalities and little is known about its impact on result and validity of the measurement. Therefore, the purpose of this study was to compare tibial slope measurements from lateral radiographs, magnetic resonance imaging (MRI) and computed tomography (CT) scans in order to better assess the clinical significance of measured tibial slope values. METHODS: Twenty patients with complete medical imaging (lateral radiographs, MRI, CT scans) undergoing anterior cruciate ligament revision surgery were included. The tibial slope of the medial and lateral plateau were measured and compared using the methods of Dejour et al. and Utzschneider et al. on lateral radiographs, by Hudek et al. and Hashemi et al. on MRI and CT scans, and by Zhang et al. on three-dimensional reconstructions of CT scans. RESULTS: Mean differences up to 5.4 ± 2.8° (P < 0.05) and 4.9 ± 2.6° (P < 0.05) between different measurement methods were found for the medial and lateral tibial slope, respectively. Depending on how the tibial shaft axis was defined, significant differences between the respective measurement methods and a relevant degree of variability were identified. Pearson correlation coefficients between the measurement methods varied distinctly from moderate to strong correlations. CONCLUSIONS: Tibial slope measurements have a high degree of variability and inaccuracy between imaging modalities and different measurement methods. Care must be taken when deciding on indications based on individual modality measurements.

Vancomycin pre-soaking of the graft reduces postoperative infection rate without increasing risk of graft failure and arthrofibrosis in ACL reconstruction.

PURPOSE: To investigate whether pre-soaking the graft in vancomycin during anterior cruciate ligament reconstruction (ACLR) reduces the postoperative infection rate and if this technique is associated with an increased rate of complications, including graft failure or arthrofibrosis. METHODS: A retrospective review of a prospective database was performed in 1779 patients who underwent ACLR over a period of 5 years, analysing the rate of postoperative deep knee infection. Group 1 and 2 both received perioperative IV antibiotics, while only group 2 underwent ACLR with grafts pre-soaked in a 5 mg/ml vancomycin solution. To analyse possible side effects associated with vancomycin use, 500 patients out of the overall study population (100 patients per year) were randomly selected and retrospectively interviewed for further postoperative complications including graft failure and arthrofibrosis as well as subjective evaluation of their knee by completing the IKDC form with a minimum mean follow-up of 37 months. RESULTS: In group 1, 22 out of 926 (2%) patients suffered a postoperative deep knee infection. In contrast, there were no postoperative infections in the second group of 853 patients (0%). 16 of 22 infections (73%) were caused by coagulase-negative Staphylococcus. Statistical analysis revealed a significantly reduced postoperative infection rate when bathing the autograft in vancomycin (p < 0.01). Analysis of the random sample revealed a significant decrease of graft failure with 8 reruptures in 257 patients (3%) in the vancomycin group compared to 16 cases of graft failure in 167 patients (10%) in the control group (p < 0.05). No differences were found in the rate of postoperative arthrofibrosis, Tegner or subjective outcome scores. CONCLUSION: Prophylactic vancomycin pre-soaking of autografts during ACLR appears to be a viable, cost-effective and safe option to reduce the rate of deep infection compared to systemic antibiotics alone. LEVEL OF EVIDENCE: III.

Individualized Anterior Cruciate Ligament Graft Matching: In Vivo Comparison of Cross-sectional Areas of Hamstring, Patellar, and Quadriceps Tendon Grafts and ACL Insertion Area.

BACKGROUND: Recent literature correlated anterior cruciate ligament (ACL) reconstruction failure to smaller diameter of the harvested hamstring (HS) autograft. However, this approach may be a simplification, as relation of graft size to native ACL size is not typically assessed and oversized grafts may impart their own complications. PURPOSE: To evaluate in vivo data to determine if the commonly used autografts reliably restore native ACL size. STUDY DESIGN: Descriptive laboratory study. METHODS: Intraoperative data of the tibial insertion area and HS graft diameter were collected and retrospectively evaluated for 46 patients who underwent ACL reconstruction with HS autografts. Magnetic resonance imaging measurements of the cross-sectional area (CSA) of the possible patellar tendon (PT) and quadriceps tendon (QT) autografts were also done for each patient. The percentages of tibial insertion site area restored by the 3 possible grafts were then calculated and compared for each individual. RESULTS: The mean ACL tibial insertion area was 107.2 mm2 (60.5-155.5 mm2). The mean CSAs of PT, HS, and QT were 33.2, 55.3, and 71.4 mm2, respectively. When all grafts were evaluated, the percentage reconstruction of the insertion area varied from 16.2% to 123.1% on the tibial site and from 25.5% to 176.7% on the femoral site, differing significantly for each graft type ( P < .05). On average, 32.8% of the tibial insertion area would have been filled with PT, 53.6% by HS, and 69.5% by QT. Based on previous cadaveric studies indicating that graft size goal should be 50.2% ± 15% of the tibial insertion area, 82.7% of patients in the HS group were within this range (36.9%, QT; 30.5%, PT), while 65.2% in the PT group were below it and 60.9% in the QT group were above it. CONCLUSION: ACL insertion size and the CSAs of 3 commonly used grafts vary greatly for each patient and are not correlated with one another. Thus, if the reconstructed ACL size is determined by the harvested autograft size alone, native ACL size may not be adequately restored. PT grafts tended to undersize the native ACL, while QT might oversize it. CLINICAL RELEVANCE: These results may help surgeons in preoperative planning, as magnetic resonance imaging measurements can be helpful in determining individualized graft choice to adequately restore the native ACL.

Suture Anchor Refixation of Meniscal Root Tears Without an Additional Portal.

The biomechanical consequences of a tear of the posterior root of the medial meniscus are comparable to that of a complete meniscectomy. The integrity of the meniscal roots is crucial to enable the important function of load sharing and shock absorption. An untreated root tear leads to extrusion and loss of function of the meniscus causing early degenerative arthritis of the respective knee compartment. Meniscal root repair can be achieved by 2 main techniques: indirect fixation using pullout sutures through a transtibial tunnel with extracortical fixation and direct fixation using suture anchors. Pullout sutures are prone to elongation or abrasion of the suture material due to the length of the bone tunnel. Current suture anchor techniques are challenging as they require an additional posterior portal with higher risk of damage to neurovascular structures. Even with the use of specially designed curved passing devices, secure insertion of the anchor is difficult. We present a technique for suture anchor refixation of the posterior root of the medial meniscus without the need for an additional posterior portal.

Reefing of the Posteromedial Capsule in Anteromedial Rotatory Instability.

The posterior oblique ligament (POL) is the main component of the posteromedial corner (PMC) of the knee and plays a crucial role in acting as a secondary restraint against translation, rotation, and valgus forces. Injuries to the PMC often occur in association with acute or chronic deficiency of the anterior cruciate ligament and may result in anteromedial rotatory instability. A surgical technique for treatment of acute and chronic injuries of the posteromedial structures was first established by Hughston in 1973. This procedure involves an advancement and reefing of the POL and adherent posterior capsule to the stout tissue of the intact medial collateral ligament, potentially using suture anchors if the POL tissue is detached from bone. Additionally, in cases of residual laxity, the semimembranosus tendon may be advanced anteriorly to improve dynamic stabilization. This procedure appears to be useful in cases of moderate posteromedial insufficiency and avoids retrieval of a medial tendon graft from the region of the medially stabilizing hamstrings or from the healthy contralateral side.

The fabella syndrome - a rare cause of posterolateral knee pain: a review of the literature and two case reports.

BACKGROUND: The purpose of this article was to evaluate the risks and benefits of non-operative treatment versus surgical excision of a fabella causing posterolateral knee pain. We performed a systematic review of literature and also present two case reports.Twelve publications were found in a PubMed literature review searching the word "fabella syndrome". Non-operative treatment and surgical excision of the fabella has been described. CASE PRESENTATION: Two patients presented to our outpatient clinic with persisting posterolateral knee pain. In both cases the presence of a fabella was identified, located in close proximity to the posterolateral femoral condyle. All other common causes of intra- and extra articular pathologies possibly causing the posterolateral knee pain were excluded.Following failure to respond to physiotherapy both patients underwent arthroscopy which excluded other possible causes for posterolateral knee pain. The decision was made to undertake surgical excision of the fabella in both cases without complication.Both patients were examined 6 month and one year after surgery with the Tegner activity score, the Visual Analogue Scale (VAS), and International Knee Documentation Committee Score (IKDC). CONCLUSION: Consistent posterolateral pain during exercise might indicate the presence of a fabella syndrome. Resecting the fabella can be indicated and is a minor surgical procedure with minimal risk. Despite good results in the literature posterolateral knee pain can persist and prevent return to a high level of sports. LEVEL OF EVIDENCE: IV, case reports and analysis of literature.

Impact of tendon suturing on the interference fixation strength of quadrupled hamstring tendon grafts.

INTRODUCTION: Interference screw fixation of soft tissue grafts has been a widely used fixation technique for cruciate ligament reconstruction. Suturing of the graft construct prior to graft fixation has been proposed to increase fixation strength; however, the effect on mechanical properties has not been well characterized. The goal of this study was to determine whether uniform suturing of the tendon graft affects (1) ultimate fixation strength of the hamstring tendon graft and (2) motion of the tendon in the bone tunnel during cyclic loading when comparing sutured grafts vs. unsutured grafts. METHOD: Eight pairs of matched mature porcine tibias (age <2 years) and eight paired fresh-frozen human quadrupled hamstring tendon grafts were used. One quadrupled graft from each pair was placed into one of two groups. In the group A a single cerclage suture 3 cm from the doubled end of the graft was placed to join the four tendon strands. In group B a heavy suture was used to tightly unite the four strands of tendon graft to provide a better grip for the interference screw during fixation. The grafts were placed in tibial bone tunnels that matched the graft's diameter and fixed with an interference screw. The looped end of the graft and the attached tibia were rigidly fixed in a material testing machine. The graft constructs were subjected to 100 cycles of 20-250 N load, followed by a load-to-failure test. In addition, a motion analysis system was used during cyclic testing to better determine the amount of elongation at the graft-tunnel interface. Statistical analysis of the failure load and stiffness and the overall elongation following cyclical loading was performed using the Wilcoxon rank sum test. Level of significance was set at p < 0.05. RESULTS: Elongation at the tendon-bone interface during sub-maximal cyclic loading was 2.4 ± 1.4 mm (unsutured) vs. 2.0 ± 0.7 mm (sutured) (p > 0.05). Failure load of the grafts without sutures (634 ± 86 N) was significantly lower than with the sutures (837 ± 183 N). Ultimate stiffness of group A (283 ± 34 N/mm) was lower than that of group B (331 ± 51 N/mm); however, this was not statistically significant (p = 0.051). CONCLUSION: This study confirms that suturing of the graft construct before interference screw fixation may increase ultimate failure load. However, an improvement of structural properties in response to cyclic loading with sub-maximal loads could not be confirmed. Clinicians using interference screw fixation may suture the graft to improve fixation strength; however, suturing does not appear to allow a more aggressive rehabilitation after surgery.