Haemophilus Parainfluenzae Septic Arthritis Following Primary All-Inside Meniscus Repair: A Case Report and Review of the Literature

Abstract

Background: Haemophilus parainfluenzae (H. parainfluenzae) is a gram-negative rod that inhabits the oral cavity. It is a common cause of respiratory tract infections and rarely is responsible for musculoskeletal infections in immunocompetent hosts. We present a case of a 17-year-old male whose postoperative course following arthroscopic all-inside meniscus repair was complicated with H. parainfluenzae septic arthritis. The infection was successfully cleared with two arthroscopic irrigation and debridements and antibiotic therapy. The patient successfully returned to full-contact high school football at five months postoperatively. To our knowledge, this represents the first reported case of H. parainfluenzae infection following an orthopaedic procedure in an adolescent.

Level of Evidence: IV

Introduction

Septic arthritis is considered an orthopaedic emergency and may cause lasting morbidity due to the sequelae of chondral damage leading to irreversible joint destruction.¹ Timely recognition and treatment is imperative to avoid long-term damage. Traditionally, the treatment of septic arthritis requires intraarticular surgical irrigation and debridement as well as the administration of intravenous antibiotics.

Haemophilus parainfluenzae (H. parainfluenzae) is a gram-negative rod found in oral flora and frequently associated with respiratory infections. H. parainfluenzae is an extremely unusual agent of musculoskeletal infection in immunocompetent hosts and has been implicated as the causative agent in only a few documented cases.² Here, we present a case of a healthy 17-year-old male whose postoperative course following all-inside meniscal repair was complicated by H. parainfluenzae septic arthritis.

Clinical Case Summary

A healthy 17-year-old male presented four weeks after sustaining a twisting injury to his right knee while wrestling at a high school tournament. Upon presentation, the patient reported right knee mechanical symptoms and pain at the medial joint line exacerbated by motion. On physical examination, the patient was tender to palpation over the medial joint line, with positive McMurray and Thessaly tests. He had full range of motion without ligamentous instability. Plain radiographs revealed a large joint effusion but were negative for fracture. Magnetic resonance imaging (MRI) demonstrated a three centimeter (cm) longitudinal peripheral posterior medial meniscus tear of the right knee. After failing six weeks of non-operative intervention (physical therapy and non-steroidal anti-inflammatory medication), the patient was indicated for arthroscopic all-inside meniscus repair.

In the operating room, hair around the operative site was clipped and skin was prepped using DuraPrep Solution. First, a diagnostic arthroscopy was performed using standard portals and confirmed the three cm longitudinal posterior medial meniscus tear. Three FasT-Fix 360 (Smith & Nephew, Andover, Massachusetts) all-inside sutures were used to repair the meniscus tear. The FasT-Fix needle was set to a depth of 16 millimeters (mm) for each vertical mattress suture. It was noted that the most anterior meniscus suture needle punctured the skin over the medial joint line; however, the device was withdrawn and the button appropriately deployed subcutaneously. After satisfactory meniscal repair, portals were closed with nylon suture. No tourniquet was utilized during the procedure and the total operative time was 41 minutes. The patient was discharged home on the day of surgery without incident. Postoperatively, the patient was instructed to wear a hinged knee brace locked in full extension when ambulating and allowed to perform active range of motion from 0-90^o when seated or supine.

The patient subsequently presented to the emergency department 25 days after his initial surgery reporting two days of progressively worsening knee pain, swelling, and inability to bear weight. Of note, he had an upper respiratory infection two days prior as well. He endorsed night sweats, decreased appetite, and was febrile (39.9°C). Laboratory tests revealed an elevated white blood cell count (20,300 with 80.8% neutrophils), an elevated erythrocyte sedimentation rate (ESR) of 34 mm/ hr, and an elevated C-reactive protein (CRP) of 13.6 mg/L. Right knee arthrocentesis was performed which revealed 6,200 total nucleated cells with 93% neutrophils, no crystals (monosodium urate or calcium pyrophosphate dihydrate), and negative gram stain. He was ultimately reassured and discharged home without antibiotics. His synovial fluid cultures became positive for H. parainfluenzae after 36 hours of growth. Due to the rarity of the pathogen, repeat knee arthrocentesis was performed in clinic, which confirmed the diagnosis of H. parainfluenzae septic arthritis. The second aspirate was only notable for an interval increase in total nucleated cells to 13,900 with 91% neutrophils. The patient was admitted for arthroscopic irrigation and debridement of the right knee with drain placement. In the operating room, the previous meniscus repair was found to be intact. There were no intra-articular signs of infection; however, a small erythematous area was noted over the medial joint line where the all-inside suture device punctured skin. A small incision was made over the area of concern without expression of purulent or infectious appearing material. Intraoperative cultures again confirmed the diagnosis of H. parainfluenzae septic arthritis. He was treated with cefazolin perioperatively and transitioned to ampicillin postoperatively at a dose of 2,000 mg every six hours at the recommendation of the Pediatric Infectious Disease team.

The patient’s clinical course was unremarkable until four days after irrigation and debridement when he reported new-onset fatigue, and his CRP increased from 3.6 mg/ L to 6.3 mg/ L over 24 hours. Given the increase in CRP and concerning systemic symptoms, the decision was made to return to the operating room for repeat irrigation and debridement of the right knee. Repeat aspiration prior to the second arthroscopic irrigation and debridement procedure was not performed. Intraoperative cultures taken during the second irrigation and debridement demonstrated no growth. The patient was discharged home five weeks after his initial meniscal repair surgery and completed a 21-day course of oral amoxicillin. At six weeks following his initial meniscal repair, full resolution of his right knee pain and swelling was reported. On examination, the patient’s passive range of motion was 0-120° with a 5° extensor lag with straight leg raise. His range of motion returned to normal four months later and he returned to full sporting activity without further incident. Six months after surgery, he started as quarterback for his high school football team and played all season without any knee-related complications.

Discussion

We present a case of a healthy 17-year-old male whose postoperative course following arthroscopic all-inside meniscus repair was complicated by H. parainfluenzae septic arthritis. To our knowledge, this represents the first reported case of H. parainfluenzae infection following an orthopaedic procedure in an adolescent.

Knee arthroscopy is a commonly performed, minimally invasive, and relatively safe procedure. Potential complications have been well-documented in the literature and include hemarthrosis, infection, and venous thromboembolic events.³ Complication rates for all patients after knee arthroscopy are low, with reported rates ranging from 0.56% to 8.2%.² The infection rate after arthroscopic all-inside meniscal repair using the FasT-Fix device has been reported to range between 3.3%-4.0% in several small case series.^2,4,5 Martin et al. delineated the risk factors for 30-day morbidity and mortality following knee arthroscopy and identified African-American race, prior operation within 30-days, increased American Society of Anesthesiologists (ASA) class, and operative time greater than 1.5 hours as predictive factors for complication.⁶ In a study of 1,002 pediatric and adolescent knee arthroscopies, a complication rate of 14.7% was found, with septic arthritis present in 0.3% of cases.⁷ Prolonged anesthesia and tourniquet times were identified as factors predictive of morbidity.⁷

Despite the high prevalence of Haemophilus as a member of normal oral flora, its low pathogenic potential makes this species an infrequent cause of disease, especially following orthopaedic procedures.² H. parainfluenzae is a fastidious organism with many requirements to ensure culture growth, including chocolate agar with factor V in the media.² Improper culture media may prohibit the diagnosis of septic arthritis secondary to unusual pathogenic agents.

Cobo et al. published a review of 18 cases of H. parainfluenzae musculoskeletal infection.² Of these 18 reported cases, only three of these cases involved prior orthopaedic surgical interventions, specifically total knee arthroplasty (2) and total hip arthroplasty (1) procedures (age range: 65-78 years).² Eight of the reported cases involved the knee, and 39% lacked clinically identifiable risk factors for H. parainfluenzae infection.² The serum WBC count was elevated in 11 patients while the CRP was elevated in only 10 patients at the time of diagnosis. The oral cavity was identified as a possible source of H. parainfluenzae septic arthritis in 28% of cases. Only one case in this series was secondary to a cutaneous infection.² Overall, H. parainfluenzae septic arthritis can present a diagnostic challenge as it typically produces a lower than normal total nucleated cell count on arthrocentesis and may take a few days to grow in culture. Additionally, as demonstrated in the previous review by Cobo et al., systemic inflammatory labs may be normal or only slightly elevated in these cases.² A high index of suspicion is often needed for a prompt diagnosis.

Upon review of the literature, only two cases of septic arthritis of the knee in adolescents attributed to H. parainfluenzae were identified.^8,9 Both of these cases did not occur following knee arthroscopy and one case was deemed presumptive H. parainfluenzae septic arthritis as the organism was never isolated from the knee. The first adolescent patient, an 18-year-old male, presented with a painful knee suspicious for gonococcal septic arthritis.⁹ He was afebrile on presentation, with a warm and swollen right knee. Furthermore, he had a painful left elbow and associated gonococcal urethritis. Following aspiration of the knee, initial gram stain and joint cultures were negative with only a few neutrophils present. However, H. parainfluenzae was isolated from his blood. His symptoms resolved after two days of penicillin therapy intravenously. Notably, chocolate agar medium was not used to assess the joint culture with the authors deeming the case ‘presumptive’ septic arthritis secondary to H. parainfluenzae.⁹ The diagnosis of septic arthritis in this case is questionable given the negative culture and resolution of symptoms with only 48 hours of intravenous antibiotics. The second case was that of an otherwise healthy 12-year-old male diagnosed with septic arthritis of a native knee.⁸ He presented afebrile with a 24-hour history of knee pain, swelling, and inability to weight bear. Laboratory tests were notable for an elevated WBC count of 38,750.⁸ While initial gram staining was negative, cultures from the joint aspirate grew Gram-negative coccobacilli on hospital day two, confirmed with re-culture with chocolate agar, and later identified as H. parainfluenzae. This patient was successfully treated with arthroscopic irrigation and debridement as well as 10-days of intravenous cefotaxime followed by three weeks of oral amoxicillin.⁸

The origin of H. parainfluenzae in our case remains uncertain. While repairing the meniscus, the FasT-Fix needle was noted to have punctured the skin. This may be seeded the joint with the organism if the preoperative skin preparation was ineffective. This route of transmission remains unlikely as H. parainfluenzae is typically found in the respiratory tract and other micro-organisms such as Staphylococcus species are much more prevalent as skin flora. Of note, the patient did report an upper respiratory illness two days prior to presentation. Blood cultures were never drawn with hematogenous seeding of the joint a definite possibility. Overall, short-term outcomes in the 18 previously documented cases of H. parainfluenzae infection in the literature have been positive, with 72.2% of patients reporting complete resolution of symptoms and return to baseline activity levels.² Longer follow-up is needed to further delineate long term outcomes following H. parainfluenzae septic arthritis of the knee.

Conclusion

The timely diagnosis and treatment of septic arthritis is paramount to prevent cartilage damage and joint destruction. Atypical pathogens pose a diagnostic challenge due to atypical laboratory values, variable culture requirements, and delayed culture growth. Here, we present a case of unusual septic arthritis of the knee secondary to the respiratory pathogen H. parainfluenzae in a 17-year-old male following arthroscopic all-inside meniscus repair. Following surgical irrigation and debridement and intravenous antibiotics, an excellent outcome was achieved with return to full contact sporting activities at five months following surgery.