Engineering Tendon Assembloids to Probe Cellular Crosstalk in Disease and Repair.

Tendons enable locomotion by transferring muscle forces to bones. They rely on a tough tendon core comprising collagen fibers and stromal cell populations. This load-bearing core is encompassed, nourished, and repaired by a synovial-like tissue layer comprising the extrinsic tendon compartment. Despite this sophisticated design, tendon injuries are common, and clinical treatment still relies on physiotherapy and surgery. The limitations of available experimental model systems have slowed the development of novel disease-modifying treatments and relapse-preventing clinical regimes. In vivo human studies are limited to comparing healthy tendons to end-stage diseased or ruptured tissues sampled during repair surgery and do not allow the longitudinal study of the underlying tendon disease. In vivo animal models also present important limits regarding opaque physiological complexity, the ethical burden on the animals, and large economic costs associated with their use. Further, in vivo animal models are poorly suited to systematic probing of drugs and multicellular, multi-tissue interaction pathways. Simpler in vitro model systems have also fallen short. One major reason is a failure to adequately replicate the three-dimensional mechanical loading necessary to meaningfully study tendon cells and their function. The new 3D model system presented here alleviates some of these issues by exploiting murine tail tendon core explants. Importantly, these explants are easily accessible in large numbers from a single mouse, retain 3D in situ loading patterns at the cellular level, and feature an in vivo-like extracellular matrix. In this protocol, step-by-step instructions are given on how to augment tendon core explants with collagen hydrogels laden with muscle-derived endothelial cells, tendon-derived fibroblasts, and bone marrow-derived macrophages to substitute disease- and injury-activated cell populations within the extrinsic tendon compartment. It is demonstrated how the resulting tendon assembloids can be challenged mechanically or through defined microenvironmental stimuli to investigate emerging multicellular crosstalk during disease and injury.

Acute Patellar Tendon Ruptures: An Update on Management.

Patellar tendon ruptures can be debilitating injuries. When incomplete, partial tears can be managed nonsurgically with immobilization and progressive rehabilitation. Although complete ruptures remain a relatively uncommon injury, they portend a high level of morbidity. Ruptures typically result from an acute mechanical overload to the extensor mechanism, such as with forced quadriceps contraction and knee flexion. However, chronically degenerated tendons are also predisposed to failure from low-energy injuries. Diagnosis can often be made clinically with recognition of a palpable defect to the tendon, localized patellar tendon tenderness, and inability to actively extend the knee. Diagnosis and surgical planning can be established with radiograph, ultrasonography, or magnetic resonance imaging. Surgical repair is the mainstay of treatment, and there have been many recent advances in repair technique, optimal reconstruction strategies, and supplemental fixation. Time to surgery for complete tears remains the most important prognosticator for success. Direct primary repair can be completed with transosseous tunnels, suture anchor repair, or end-to-end repair. Tendon reconstruction can be achieved with or without mechanical or biologic augments. Rehabilitation programs vary in specifics, but return to sport can be expected by 6 months postoperatively.

Modified gastro-soleus turn-down flap for chronic or neglected achilles tendon ruptures.

BACKGROUND: Achilles' tendon chronic rupture is a common entity that is usually misdiagnosed or mistreated. Hence, she was presented to us later or with complications affecting her gait. Surgical resection is needed to either bridge the gap or reinforce the strength of the tendon repair. OBJECTIVES: Our study's goal was to assess the clinical results of repairing chronic Achilles' tendon lesions employing the middle segment of the proximal portion of the tendon (gastro-soleus), as a turn-down flap. METHODS: Our prospective interventional single arm study included 18 patients with chronic Achilles' tendon rupture attending at Al-Azhar university hospitals in Cairo, Egypt from May 2020 to April 2023. Diagnosis of the patients was confirmed by radiographic and clinical investigations. They were all treated with the same open reconstruction procedure using a modified GSF. The average follow-up was 12 months. The results of this study were assessed by the Achilles tendon rupture score (ATRS), American Orthopedic Foot and Ankle Society (AOFAS) score, and capacity to perform repeated heel raises on the affected side. RESULTS: The mean operative time was 72.77 min. The median (IQR) time of reconstruction was 10 (8-12) after the injury. The median (IQR) length of flab was 4.5 (4.3-5) 9 (Table 2). No intraoperative complications occurred. The typical follow-up period was 12 months (6-18 months). In terms of the ATRS, we found a significant reduction from 82.8 ± 3 preoperatively to 20.8 ± 6.7 at 12 months postoperatively (P value = 0.001). As regards the AOFAS score, it was increased from 49.5 ± 10 preoperatively to 83.8 ± 8.5 12 months postoperatively (P = 0.001). In terms of the post operative complications, there was no re-rupture. Two patients experienced superficial wound infection which improved with daily dressing and antibiotics. Additionally, two patients had slight ankle stiffness four months after the operation, which improved after programmed rehabilitation at the sixth month. CONCLUSION: The modified GSTF is a simple, safe, well-tolerated and effective method of treatment with excellent functional results and greater patient content.

Effects of evidence-based nursing care interventions on wound pain and wound complications following surgery for finger tendon injury.

We conducted this study aimed to examine the impact of evidence-based nursing interventions on postoperative wound pain and complications after surgery for finger tendon injury. A total of 86 patients treated for finger tendon injuries at our hospital from January 2021 to October 2023 were selected and randomly divided into an experimental group and a control group. The control group received conventional nursing care, while the experimental group received evidence-based nursing interventions. The study compared the postoperative wound pain intensity, incidence of complications and patient satisfaction with nursing care between the two groups. The analysis revealed that compared with conventional care, evidence-based nursing interventions significantly reduced the level of wound pain (p = 0.034) and the incidence of complications (4.65% vs. 18.60%, p = 0.043). It also increased patient satisfaction with the nursing care (97.67% vs. 83.72%, p = 0.026). The study indicates that the application of evidence-based nursing interventions for patients with finger tendon injuries can reduce postoperative wound pain, decrease the incidence of complications and enhance patient satisfaction with nursing care.

Flexor Injury Rehabilitation Splint Trial (FIRST): protocol for a pragmatic randomised controlled trial comparing three splints for finger flexor tendon repairs.

BACKGROUND: Without surgical repair, flexor tendon injuries do not heal and patients' ability to bend fingers and grip objects is impaired. However, flexor tendon repair surgery also requires optimal rehabilitation. There are currently three custom-made splints used in the rehabilitation of zone I/II flexor tendon repairs, each with different assumed harm/benefit profiles: the dorsal forearm and hand-based splint (long), the Manchester short splint (short), and the relative motion flexion splint (mini). There is, however, no robust evidence as to which splint, if any, is most clinical or cost effective. The Flexor Injury Rehabilitation Splint Trial (FIRST) was designed to address this evidence gap. METHODS: FIRST is a parallel group, superiority, analyst-blind, multi-centre, individual participant-randomised controlled trial. Participants will be assigned 1:1:1 to receive either the long, short, or mini splint. We aim to recruit 429 participants undergoing rehabilitation following zone I/II flexor tendon repair surgery. Potential participants will initially be identified prior to surgery, in NHS hand clinics across the UK, and consented and randomised at their splint fitting appointment post-surgery. The primary outcome will be the mean post-randomisation score on the patient-reported wrist and hand evaluation measure (PRWHE), assessed at 6, 12, 26, and 52 weeks post randomisation. Secondary outcome measures include blinded grip strength and active range of movement (AROM) assessments, adverse events, adherence to the splinting protocol (measured via temperature sensors inserted into the splints), quality of life assessment, and further patient-reported outcomes. An economic evaluation will assess the cost-effectiveness of each splint, and a qualitative sub-study will evaluate participants' preferences for, and experiences of wearing, the splints. Furthermore, a mediation analysis will determine the relationship between patient preferences, splint adherence, and splint effectiveness. DISCUSSION: FIRST will compare the three splints with respect to clinical efficacy, complications, quality of life and cost-effectiveness. FIRST is a pragmatic trial which will recruit from 26 NHS sites to allow findings to be generalisable to current clinical practice in the UK. It will also provide significant insights into patient experiences of splint wear and how adherence to splinting may impact outcomes. TRIAL REGISTRATION: ISRCTN: 10236011.

Studying Edema Formation After Release of the Infraspinatus Muscle as an Experimental Model of Rotator Cuff Lesions in Sheep: A Histological Analysis.

BACKGROUND: Muscle edema formation and inflammatory processes are early manifestations of acute rotator cuff lesions in sheep. Histological analysis of affected muscles revealed edema formation, inflammatory changes, and muscle tissue disruption in MRs. HYPOTHESIS: Edema contributes to inflammatory reactions and early muscle fiber degeneration before the onset of fatty infiltration. STUDY DESIGN: Controlled laboratory study. METHODS: Osteotomy of the greater tuberosity, including the insertion of the infraspinatus tendon, was performed on 14 sheep. These experimental animal models were divided into 2 groups: a nontrauma group with surgical muscle release alone (7 sheep) and a trauma group with standardized application of additional trauma to the musculotendinous unit (7 sheep). Excisional biopsy specimens of the infraspinatus muscle were taken at 0, 3, and 4 weeks. RESULTS: Edema formation was histologically demonstrated in both groups and peaked at 3 weeks. At 3 weeks, signs of muscle fiber degeneration were observed. At 4 weeks, ingrowth of loose alveolar and fibrotic tissue between fibers was detected. Fatty tissue was absent. The diameter of muscle fibers increased in both groups, albeit to a lesser degree in the trauma group, and practically normalized at 4 weeks. Immunohistology revealed an increase in macrophage types 1 and 2, as well as inflammatory mediators such as prostaglandin E2 and nuclear factor kappa-light-chain-enhancer of activated B cells. CONCLUSION: Early muscle edema and concomitant inflammation precede muscle fiber degeneration and fibrosis. Edema formation results from tendon release alone and is only slightly intensified by additional trauma. CLINICAL RELEVANCE: This study illustrates that early edema formation and inflammation elicit muscle fiber degeneration that precedes fatty infiltration. Should this phenomenon be applicable to human traumatic rotator cuff tears, then surgery should be performed as soon as possible, ideally within the first 21 days after injury.

Surgical treatment of distal hamstring tendon injuries yield a higher return-to-sports rate: A systematic review.

PURPOSE: The purpose of this study is to compare the patient-reported outcomes and return to sports of the conservative and surgical treatment of distal hamstring tendon injuries. METHODS: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, two reviewers searched PubMed, Scopus and Virtual Health Library databases in January 2023. Clinical studies evaluating conservative or surgical management outcomes of distal hamstring tendon injuries were considered eligible for this systematic review if predefined criteria were fulfilled: (1) published in English or Spanish; (2) evaluated any of the following: patient-reported outcomes, return-to-sports rate (RTS-R) or return-to-sports time (RTS-T). Data were presented in tables using absolute values from individual studies and derived pooled percentages. RESULTS: Eighteen studies were included for 67 patients and 68 distal hamstring tendon injuries. Initially, 39 patients (58.2%) underwent surgical treatment, whereas 28 (41.8%) were treated conservatively. Among conservative treatment patients, 15 failed and had to be operated on (53.6%), all with distal semitendinosus tendon injuries. Anchor fixation was the technique of choice in 20 lesions (36.4%), tenodesis in 16 (29.1%), tenectomy in 14 (25.5%) and sutures were preferred in five (9%). Thirteen out of 28 patients (46.4%) undergoing initial conservative treatment returned to sports at a mean of 3.6 months (range 1 week to 12 months), in contrast to surgical treatment, in which 36 out of 39 patients (92.3%) returned at a mean of 4.2 months (range 6 weeks to 12 months). Additionally, 14 of 15 patients (93.3%) converted to surgical treatment after failed conservative treatment returned to sports at a mean of 7.6 months after injury. CONCLUSION: Initial surgical treatment of distal hamstring tendon injuries yields a high RTS-R (92.3%) at a mean of 4.2 months. Furthermore, 15 out of 28 patients (53.6%) initially treated conservatively had to be operated on, delaying the RTS-T (mean 7.6 months after injury) without affecting their RTS-R. LEVEL OF EVIDENCE: IV.

Comparison of percutaneous and open repair of Achilles tendon rupture: results and complications from a single institution.

BACKGROUND: The Achilles tendon is the strongest tendon in the human body, but it is prone to injury, especially in modern times when recreational sports are growing in popularity. As a result, Achilles tendon rupture is becoming an increasingly common medical problem in modern society. The main objective of this study was to compare the outcomes of percutaneous repair and open repair for the treatment of Achilles tendon rupture. METHODS: A retrospective study was conducted involving a total of 316 patients who had undergone surgical treatment for Achilles tendon rupture between 2013 and 2021. The data collected from the medical history of these patients included the type of surgical procedure, the mechanism of injury, the age and sex of the patients, the time spent in the hospital, and any possible complications of the surgical treatment (such as infections, reruptures, or sural nerve injuries). RESULTS: The study revealed that there was no significant difference between percutaneous and open surgical approaches in terms of sural nerve injury. However, there was a statistically significant advantage of the percutaneous method in terms of the number of infections, which was significantly lower than that of the open method. Additionally, the median length of hospital stay was found to be four days longer with the open approach. However, the study noted that a statistically significant advantage of the percutaneous method for rerupture could not be established due to the small number of patients with rerupture and the insufficient ratio of patients with rerupture in relation to the size of the observed population. CONCLUSIONS: Percutaneous repair is an effective treatment option for Achilles tendon rupture and has outcomes equal to or better than those of open repair. Therefore, this approach is recommended as the preferred method of treatment due to the presence of fewer complications, provided that the indications for this technique are appropriate.

Management of Checkrein Deformity.

Checkrein deformity is characterized by the dynamic status of the hallux, in which flexion deformity is aggravated by ankle dorsiflexion and relieved by ankle plantarflexion. In most cases, a checkrein deformity occurs secondary to trauma or following surgery. It has been suggested that the flexor hallucis longus tendon tethers or entraps scar tissue or fracture sites. Improvement with conservative treatment is difficult once the deformity has already become entrenched, and surgical management is usually required in severe cases. Various surgical options are available for the correction of checkrein deformities. It includes a simple release of adhesion at the fracture site; lengthening of the flexor hallucis longus by Z-plasty at the fracture site combined with the release of adhesion; lengthening of the flexor hallucis longus by Z-plasty at the midfoot, retromalleolar, or tarsal tunnel area; and flexor hallucis longus tenotomy with interphalangeal arthrodesis for recurrent cases. This review aimed to summarize the overall etiology, relevant anatomy, diagnosis, and treatment of checkrein deformities described in the literature.

Complications of flexor tendon repair.

This article reviews and highlights complications of flexor tendon repairs. Although the outcomes of flexor tendon repairs have improved over the years, fair or poor functional outcomes are seen, especially in patients whose trauma involves multiple structures of the hand and in zone 5 with multiple tendon lacerations. Rupture of the flexor tendon after repair is no longer a major problem if current repair principles are carefully adhered to. Different degrees of adhesion formations and interphalangeal (IP) joint stiffness still occur in a few patients. Early active postoperative mobilization and use of a shorter splint with sparing of the wrist are effective measures to prevent adhesion formation and IP joint stiffness. Given the overall poor results and high rate of complications with flexor digitorum profundus (FDP) repairs in zone 1, a direct repair of the FDP tendon to any short remnant of the distal insertion with 10-strand or even stronger core suture repair is adopted by many units.

Delayed Diagnosis of Complete Achilles Tendon Rupture in a Teenage Athlete: A Case Report of Nonoperative Treatment.

CASE: A 19-year-old female athlete experienced calf pain during sport. A complete Achilles tendon rupture was diagnosed 4 weeks after injury. Ultrasound revealed discontinuity of the Achilles tendon with 2.0 cm of diastasis, persisting in plantarflexion. Plantarflexion immobilization was initiated, and progressive dorsiflexion was used until 10 weeks from injury. At 1 year from injury, ankle magnetic resonance imaging revealed a contiguous tendon, the patient was pain-free, and had returned to high-level athletics with equivalent sport performance relative to her preoperative status. CONCLUSION: Certain Achilles tendon ruptures in young people may be treated nonoperatively with good clinical outcomes, even if diagnosis and immobilization are delayed and tendon diastasis persists in maximum plantarflexion.

[Anatomical and biomechanical characteristics of plantaris tendon and its application in ligament reconstruction].

Objective: To improve the clinical utility of the plantaris tendon mainly by summarizing its anatomical characteristics, biomechanical properties, harvesting methods, and its applications in ligament reconstruction. Methods: The relevant literature from domestic and international databases regarding the anatomical and biomechanical characteristics of the plantaris tendon and its applications in ligament reconstruction was comprehensively reviewed and systematically summarized. Results: The plantaris tendons have an absence. The majority of plantaris tendon forms a fan-shape on the anterior and medial sides of the Achilles tendon and terminates at the calcaneal tuberosity. There are significant differences in biomechanical parameters between plantaris tendon with different numbers of strands, and multi strand plantaris tendon have significant advantages over single strand tendon. The plantaris tendon can be harvested through proximal and distal approaches, and it is necessary to ensure that there are no obvious anatomical variations or adhesions in the surrounding area before harvesting. The plantaris tendon is commonly utilized in ligament reconstruction around the ankle joint or suture reinforcement for Achilles tendon rupture, with satisfactory effectiveness. There is limited research on the use of plantar tendon in the reconstruction of upper limb and knee joint ligaments. Conclusion: The plantaris tendon is relatively superficial, easy to be harvested, and has less impact on local function. The plantaris tendon is commonly utilized in ligaments reconstruction around the ankle joint or suture reinforcement for Achilles tendon rupture. The study on the plantaris tendon for upper limbs and knee joints ligament reconstruction is rarely and require further research.

Replacement of tibialis cranialis tendon with polyester, silicone-coated artificial tendon preserves biomechanical function in rabbits compared to tendon excision only.

BACKGROUND: Artificial tendons may be an effective alternative to autologous and allogenic tendon grafts for repairing critically sized tendon defects. The goal of this study was to quantify the in vivo hindlimb biomechanics (ground contact pressure and sagittal-plane motion) during hopping gait of rabbits having a critically sized tendon defect of the tibialis cranialis and either with or without repair using an artificial tendon. METHODS: In five rabbits, the tibialis cranialis tendon of the left hindlimb was surgically replaced with a polyester, silicone-coated artificial tendon (PET-SI); five operated control rabbits underwent complete surgical excision of the biological tibialis cranialis tendon in the left hindlimb with no replacement (TE). RESULTS: At 8 weeks post-surgery, peak vertical ground contact force in the left hindlimb was statistically significantly less compared to baseline for the TE group (p = 0.0215). Statistical parametric mapping (SPM) analysis showed that, compared to baseline, the knee was significantly more extended during stance at 2 weeks post-surgery and during the swing phase of stride at 2 and 8 weeks post-surgery for the TE group (p < 0.05). Also, the ankle was significantly more plantarflexed during swing at 2 and 8 weeks postoperative for the TE group (p < 0.05). In contrast, there were no significant differences in the SPM analysis among timepoints in the PET-SI group for the knee or ankle. CONCLUSIONS: Our findings suggest that the artificial tibialis cranialis tendon effectively replaced the biomechanical function of the native tendon. Future studies should investigate (1) effects of artificial tendons on other (e.g., neuromuscular) tissues and systems and (2) biomechanical outcomes when there is a delay between tendon injury and artificial tendon implantation.

Risk factors and clinical characteristics of surgical site infections in athletes undergoing Achilles tendon repair surgery.

Achilles tendon ruptures are common in athletes, requiring surgical intervention. However, the risk of surgical site infections (SSIs) post-surgery poses significant challenges. This study aims to analyse the risk factors and microbial aetiology associated with SSIs in athletes undergoing Achilles tendon repair. A comprehensive retrospective analysis was conducted from May 2021 to July 2023. The study included 25 patients with SSIs (case group) and 50 patients without SSIs (control group) post Achilles tendon repair surgery. Inclusion criteria encompassed patients with medically confirmed Achilles tendon ruptures who underwent surgical repair. Exclusion criteria included prior tendon pathologies and significant chronic illnesses. Diagnostic criteria for SSIs involved symptoms like elevated body temperature and localized tenderness, along with laboratory confirmations such as positive microbiological cultures. The study utilized VITEK® 2 for bacterial identification and involved statistical analyses like univariate and multivariate logistic regression. The study identified Staphylococcus aureus as the primary pathogen in SSIs. Significant risk factors included lack of prophylactic antibiotic use, presence of diabetes, open wounds and prolonged surgery duration. Univariate analysis revealed stark contrasts in these factors between infected and non-infected groups, while multivariate analysis underscored their importance in SSI development. S. aureus emerged as the predominant pathogen in SSIs post Achilles tendon repair. Critical risk factors such as absence of prophylactic antibiotics, diabetes, open wounds and extended surgery duration play a vital role in SSIs. Addressing these factors is essential for better postoperative outcomes in Achilles tendon repair surgeries.

Surgical management of chronic Achilles tendon rupture: evidence-based guidelines.

BACKGROUND: Chronic Achilles tendon ruptures (CATR) often require surgical intervention to restore function. Despite numerous treatment modalities available, the optimal management strategy remains controversial given the limited high-quality evidence available. This article aims to provide evidence-based guidelines for the surgical management of CATR through a comprehensive systematic review of the available data. The consensus reached by synthesizing the findings will assist clinicians in making informed decisions and improving patient outcomes. METHODS: A group of 9 foot surgeons in three continents was consulted to gather their expertise on guidelines regarding the surgical management of CATR. Following the proposal of 9 clinical topics, a thorough and comprehensive search of relevant literature published since 1980 was conducted for each topic using electronic databases, including PubMed, MEDLINE, and Cochrane Library, to identify relevant studies published until 1 October 2023. All authors collaborated in drafting, discussing, and finalizing the recommendations and statements. The recommendations were then categorized into two grades: grade a (strong) and grade b (weak), following the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) concept. Additionally, feedback from 21 external specialists, who were independent from the authors, was taken into account to further refine and finalize the clinical guidelines. RESULTS: Nine statements and guidelines were completed regarding surgical indications, surgical strategies, and postoperative rehabilitation protocol. CONCLUSION: Based on the findings of the systematic review, this guideline provides recommendations for the surgical management of CATR. We are confident that this guideline will serve as a valuable resource for physicians when making decisions regarding the surgical treatment of patients with CATR.

Endoscopic peroneus brevis tendon transfer for chronic ruptures of the Achilles tendon: surgical technique.

Chronic Achilles tendon rupture is usually defined as a rupture diagnosed 4-6 weeks after injury. The management of chronic Achilles tendon rupture (CATR) is a topic of hot debate, and no consensus has been achieved. Surgical management of CATR is recommended. Several approaches, techniques, and grafts have been described. Open techniques carry a high risk of wound breakdown, infection, and necessitate long rehabilitation times. Surgical techniques with smaller incisions to reduce the risk of scar fibrosis, pain, and infection are becoming common. The ipsilateral tendon of the hallux flexor longus and the peroneus brevis is commonly used. Endoscopic transfer of the peroneus brevis tendon is an innovative alternative to other procedures, with comparable results of other autografts even in elite athletes. The tendon of the peroneus brevis is harvested by tendoscopy before performing a calcaneal tendon endoscopy and fixing the graft in a calcaneal tunnel using an interference screw. After surgery, an anterior splint is placed for 3 weeks with immediate forefoot weight bearing. The rehabilitation starts on the 15th postoperative day.

Editorial Commentary: Artificial Intelligence Models Using Machine Learning Can Improve Preoperative Identification of Subscapularis Pathology.

Subscapularis pathology is difficult to diagnose, in part because of decreased sensitivity and accuracy in identifying tears with magnetic resonance imaging (MRI) when compared to other cuff tendons. Artificial intelligence evaluation of patient physical examination and MRI data using a machine learning model shows that arthroscopically confirmed partial- or full-thickness subscapularis tears are highly associated with abnormal subscapularis tendon length, long head of the biceps tears, and subscapularis fatty atrophy, and on physical examination, with weakness with internal rotation and positive lift-off, belly press, and bear hug tests. Today, physicians may use machine learning as a tool, but this model may not currently be sufficient to drastically change practice. However, with continued research and development, which is occurring rapidly, similar models could aid physicians in timely identification of pathology and optimization of preoperative planning, as well as physician training and education.

Open lateral condyle Hoffa's fracture with intra-articular patella dislocation, quadriceps tendon rupture and PCL avulsion.

We present a rare case of open lateral condyle Hoffa's fracture with concurrent patellar intra-articular dislocation, quadriceps rupture and posterior cruciate ligament (PCL) avulsion. The early adolescent male sustained these injuries in a road traffic accident. Diagnostic evaluation and a multidisciplinary approach guided treatment decisions. The patient underwent single-stage open reduction and internal fixation for the lateral condyle Hoffa's fracture and quadriceps tendon repair, while conservative management was chosen for the PCL avulsion. At the 1-year follow-up, the patient exhibited improved knee function.This case underscores the management of complex knee injuries and contributes to understanding unique injury patterns, enhancing patient care.

The Delayed Presentation of Achilles Tendon Ruptures Is Associated With Marked Alterations in the Gene Expression of COL1A1, MMPs, TIMPs, and IL-6.

BACKGROUND: Both acute and chronic Achilles tendon ruptures are affected by alterations in the extracellular matrix during the healing process of the tendon. Yet, these alterations in gene expression patterns are not well characterized. PURPOSE: To characterize temporal and spatial differences in gene expression patterns after an Achilles tendon rupture and to evaluate if cells from chronic Achilles tendon ruptures have the same ability to form new tendon tissue (tendon constructs) as healthy tendon cells. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 35 patients with surgically treated Achilles tendon ruptures were included in the study and divided into 3 groups: acute (<4 weeks), short-term chronic (1-6 months), and long-term chronic (>6 months). Biopsy specimens were collected during surgical repair and were used to analyze the gene expression within the different groups and to compare mRNA levels in the proximal and distal tendon ends. A complementary in vitro experiment was performed to evaluate if cells from chronic Achilles tendon ruptures can form tendon constructs. RESULTS: The mRNA levels for COL1A1 and COL3A1 were significantly higher in the short-term chronic group compared with the acute group (P < .05). Both MMP-1 and MMP-13 had the highest mRNA levels in the acute group (P < .01) compared with the long-term chronic group, while MMP-2 had the highest mRNA level in the short-term chronic group. Significant differences between the proximal and distal tendon ends were only detected for the monocyte and macrophage marker CD163 (P < .05), which was more expressed proximally. Cells extracted from chronic Achilles tendon ruptures displayed a similar ability and effectiveness to form tendon constructs as healthy tendon cells. CONCLUSION: A high collagenase gene activity after an Achilles tendon rupture indicated possible rapid matrix degradation in the acute phase. Chronic ruptures appeared to initiate the healing process even before treatment, indicated by the higher expression of collagen in the short-term chronic group. Cells from chronic Achilles tendon ruptures also displayed an ability to form new tendon tissue in vitro. CLINICAL RELEVANCE: The study shows a rapid increase in collagenase gene expression, which could lead to matrix degradation that continues for months after an Achilles tendon rupture.