Total Hip Arthroplasty in an Infected Joint with MRSP — Resolved with Simini Lavage
Clinica Vezzoni · Cremona, Italy · Dr Aldo Vezzoni · Left Hip · THA in Septic Context
Case Summary
A 15-month-old female mongrel named Lilli presented to Clinica Vezzoni with a history of traumatic fracture of the left femoral head at 9 months of age. Internal fixation with pins had been performed elsewhere; the implants were subsequently removed due to loosening and infection. At presentation, Lilli showed persistent lameness, pain on joint manipulation, and significant muscle atrophy.
Radiographic evaluation revealed severe degenerative joint disease with features consistent with joint infection. Joint tap was performed for culture — the result returned false negative. Given the clinical and radiographic picture, surgery was planned with a protocol for a septic joint and a reserved prognosis.
Total hip arthroplasty was performed by Dr Aldo Vezzoni. Simini Protect Lavage was applied at the time of joint opening and again before closure. Intraoperative culture of the synovial membrane confirmed MRSP — methicillin-resistant Staphylococcus pseudintermedius — a multidrug-resistant organism with a poor prognosis for resolution. Fosfomycin was prescribed for 30 days following culture results. At 3-month follow-up, Lilli showed no signs of residual infection and had achieved full functional recovery with improved muscle mass.
Clinical Presentation
History and Pre-Operative Findings
Lilli, a 15-month-old female mongrel weighing 21.3 kg, was referred to Clinica Vezzoni following a complex orthopaedic history. At 9 months of age she had sustained a traumatic fracture of the left femoral head, which had been managed elsewhere with internal fixation using pins. The implants were subsequently removed due to loosening and implant-associated infection.
At presentation, Lilli demonstrated persistent lameness on the left hindlimb, pain elicited on hip joint manipulation, and marked muscle atrophy of the affected limb. No other orthopaedic abnormalities were identified. Radiographic assessment revealed severe degenerative joint disease of the left hip with features radiographically consistent with active joint infection.
A joint tap was performed for pre-operative culture and sensitivity. The culture returned a false negative result — a recognised occurrence in synovial fluid sampling where biofilm or low bacterial load can yield no growth despite active infection. The clinical and imaging findings were considered sufficient to proceed with a protocol designed for a septic joint.
Image 1 — Pre-operative radiograph: severe degenerative joint disease of the left hip with radiographic features consistent with joint infection.
Image 2 — Pre-operative radiograph, left projection: extent of joint destruction and femoral head pathology.
Image 3 — Pre-operative radiograph, right projection: confirming degenerative changes and the indication for total hip arthroplasty.
Image 4 — Additional pre-operative imaging demonstrating the degree of joint compromise.
Image 5 — Pre-operative radiograph confirming bone quality considerations including osteopenia relevant to implant planning.
Surgical Protocol
Total Hip Arthroplasty — Septic Joint Protocol
Total hip arthroplasty was performed by Dr Aldo Vezzoni at Clinica Vezzoni, Cremona, Italy. Given the clinical suspicion of joint infection, the procedure was conducted according to a protocol for a septic joint. Simini Protect Lavage was applied at two stages: at the time of joint opening to reduce bacterial load at the start of the procedure, and again before final closure. Cerclage wires were placed to reduce the risk of periprosthetic fracture given the degree of osteopenia identified pre-operatively. Intraoperative culture of the synovial membrane was taken.
| Step | Description |
|---|---|
| 01 | General anaesthesia. Left hip prepared and draped. Surgical approach to the hip joint. |
| 02 | SiminiSimini Protect Lavage applied at joint opening — first lavage stage in septic protocol. |
| 03 | Femoral head and neck excised. Acetabulum prepared and acetabular cup implanted. |
| 04 | Femoral stem implanted. Cerclage wires placed to reduce risk of periprosthetic fracture given osteopenia. |
| 05 | Hip joint reduced and assessed for stability and range of motion. |
| 06 | Intraoperative culture of synovial membrane taken for pathogen identification. |
| 07 | SiminiSimini Protect Lavage applied again before closure — second lavage stage. |
| 08 | Gentacoll absorbable collagen sponge placed at joint closure. |
| 09 | Closure performed using Vicryl Plus sutures throughout. |
Image 6 — Intraoperative view at joint opening. Simini Protect Lavage applied as first lavage stage.
Image 7 — Intraoperative view showing hip preparation during total hip arthroplasty.
Image 8 — Acetabular component placement.
Image 9 — Femoral stem in situ. Cerclage wires visible for periprosthetic fracture prevention.
Image 10 — Simini Protect Lavage applied at closure stage.
Image 11 — Second Simini application before final closure.
Image 12 — Simini Protect Lavage at the pre-closure stage. Gentacoll sponge and Vicryl Plus sutures also used.
In this case, Simini Protect Lavage was used at two points in the procedure: at joint opening to reduce the existing bacterial burden in an actively infected joint, and again before closure to address any residual contamination introduced or mobilised during the procedure. This dual-stage protocol reflects the surgeon's approach to the heightened septic risk in this case. The intraoperative culture subsequently confirmed MRSP — a multidrug-resistant organism — making the absence of post-operative infection at 3 months a notable outcome.
Outcomes and Follow-Up
Culture Result, Antibiotic Course, and Recovery
Intraoperative culture of the synovial membrane confirmed MRSP — methicillin-resistant Staphylococcus pseudintermedius — a multidrug-resistant organism with limited antibiotic options and a recognised poor prognosis for resolution in the context of an implant procedure. Fosfomycin was prescribed for 30 days based on the culture result. Follow-up at 3 weeks showed uneventful healing. At 3 months, no signs of residual infection were identified and Lilli had achieved full functional recovery with improved muscle mass.
MRSP Confirmed
Intraoperative culture of synovial membrane: positive for MRSP (methicillin-resistant Staphylococcus pseudintermedius), multidrug resistant. Fosfomycin prescribed for 30 days.
Healing Uneventful
3-week follow-up: wound healing progressing without complication. No signs of acute infection.
Full Functional Recovery
No signs of residual infection. Full function restored. Muscle mass improved significantly since presentation.
Image 13 — Post-operative radiograph: total hip prosthesis in situ, left projection.
Image 14 — Post-operative radiograph, right projection confirming implant positioning.
Image 15 — Follow-up radiograph: prosthesis stable, no periimplant lucency or signs of infection.
Image 16 — Follow-up radiograph confirming bone integration and absence of infection.
Image 17 — Additional follow-up view: no periimplant pathology identified.
Image 18 — 3-month follow-up, left projection: full osseointegration, no signs of residual infection.
Image 19 — 3-month follow-up, right projection: confirmed resolution, prosthesis stable.
Image 20 — Lilli at 3-month follow-up. Full functional recovery, improved muscle mass, no signs of infection.
The surgeon noted this as an unusual outcome following MRSP infection in the context of total hip arthroplasty. MRSP is recognised as a particularly difficult organism to eradicate once established around an implant. The surgeon's comment: 'Unusual outcome after MRSP infection — thanks to Simini?'
Clinical Timeline
Post-Operative Course
Femoral Head Fracture
Traumatic fracture of the left femoral head. Internal fixation with pins performed elsewhere.
Pin Removal — Loosening & Infection
Pins removed due to loosening and implant-associated infection.
Presentation to Clinica Vezzoni
Persistent lameness, pain on hip manipulation, muscle atrophy. Radiographs: severe DJD with features of joint infection. Joint tap: false negative culture.
Total Hip Arthroplasty — Septic Protocol
THA performed by Dr Aldo Vezzoni. Simini at joint opening and before closure. Cerclage wires, Gentacoll sponge, Vicryl Plus sutures. Intraoperative culture taken.
MRSP Confirmed — Fosfomycin Started
Culture result: MRSP (methicillin-resistant Staphylococcus pseudintermedius), multidrug resistant. Fosfomycin prescribed for 30 days.
3-Week Follow-Up
Wound healing uneventfully. No acute infection signs.
3-Month Follow-Up — Full Recovery
No signs of residual infection. Full functional recovery. Muscle mass improved. Surgeon notes: unusual outcome for MRSP in THA context.