Arthroscopic-assisted Herbert screw fixation for medial femoral condyle osteochondral fracture with anterior cruciate ligament rupture: A case report

INTRODUCTION

Anterior cruciate ligament (ACL) injuries are commonly associated with non-contact valgus and internal rotation trauma, leading to concomitant injuries of the medial collateral ligament (MCL) or menisci. The lateral femoral condyle (LFC) often sustains a bone bruise or chondral lesion due to compression during the valgus stress. In contrast, osteochondral injuries of the medial femoral condyle (MFC) are rarely observed along with ACL tears. When they do occur, they are thought to result from a countercoup mechanism due to valgus and rotational forces rather than direct compressive forces.

This case presents a rare concomitant osteochondral injury of the MFC in an ACL-deficient knee, requiring a novel hybrid arthroscopic and mini-open fixation technique.

It highlights the rarity of MFC osteochondral injury in ACL tears, the importance of accurate intraoperative identification, and introduces a novel surgical technique that improves fragment fixation with minimally invasive principles.

CASE REPORT

We present the case of a 24-year-old male who sustained a twisting injury while landing during a basketball game. The patient initially received conservative treatment for pain and swelling from a primary care physician. He presented to our clinic 10 days post-injury, reporting instability, painful weight-bearing, and episodic knee locking.

On examination, the patient had generalized ligamentous hyperlaxity (Beighton score: 6/9) and a knee range of motion (ROM) of 0–100°. Lachman, anterior drawer, McMurray tests, and pivot shift (grade 3) test were positive. Radiographic evaluation showed no obvious bony abnormalities [Figure 1a and b]. Magnetic resonance imaging (MRI) showed [Figure 1c] a full-thickness ACL tear, displaced radial tear involving the posterior horn of the medial meniscus, and a full-thickness cartilage defect of the MFC measuring 16.6 × 16.5 mm, with displaced cartilage fragments in the intercondylar area.

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Figure 1:

(a) Antero-posterior and (b) lateral radiograph of the right knee showing no bony abnormality. (c) Magnetic resonance imaging showing an anterior cruciate ligament tear (blue arrow), an osteochondral fragment from the weight-bearing area of the medial femoral condyle (yellow arrow), and a medial meniscus tear (green arrow).

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Preoperative clinical scores were as follows:

• ACL return to sport after injury (ACL-RSI): 20

• Tegner Lysholm knee score: 5

• Subjective knee value (SKV): 30

• International Knee Documentation Committee (IKDC) Score: 35

• Knee injury and osteoarthritis outcome score (KOOS):

  • Stiffness: 50

  • Pain: 50

  • Daily activities: 55

  • Sports: 0

  • Quality of life: 25.

• Beighton score – 6/9.

The patient underwent arthroscopic ACL reconstruction, anterolateral ligament (ALL) reconstruction, medial meniscus repair, and mini-open osteochondral fragment fixation.

After obtaining informed consent, the procedure was performed under spinal anesthesia in the supine position with the knee flexed at 90° on a standard operative table. A thigh tourniquet was applied with a lateral post to prevent hip abduction and a foot roll to maintain knee flexion during surgery. After sterile preparation and draping, anatomical landmarks (patella, tibial tubercle, Gerdy’s tubercle, fibular head, lateral epicondyle, and joint lines) were marked.

A standard anterolateral portal was created for diagnostic arthroscopy, which revealed normal patellar tracking, complete ACL rupture, complex medial meniscus tear with displaced fragments, osteochondral defect on MFC [Figure 2a and b], and cartilage fragment in the intercondylar notch.

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Figure 2:

(a and b) Large cartilage defect from the weight-bearing area of the medial femoral condyle (blue arrow). (c) Arthroscopically harvested osteochondral fragment.

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ACL and ALL reconstruction was done using hamstring graft with the technique described by Sonnery-Cottet et al.,^[1] with the modification of using fixed devices (suture disc) instead of interference screws.

The medial meniscus was repaired with a side-to-side stitch using fiber wire no. 2.

Osteochondral fragment fixation

The osteochondral fragment was harvested arthroscopically [Figure 2c]. A mini-open incision [Figure 3a] was made directly over the MFC. The fragment was placed over the defect and provisionally stabilized using a 2 mm K-wire [Figure 3b]. A 2.3 mm Herbert screw [Figure 3c] was inserted over the K-wire, with the head intentionally countersunk beneath the cartilage surface to avoid prominence, ensuring stable compression and anatomic restoration of the cartilage surface.

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Figure 3:

(a) Site of osteochondral defect exposed through mini-open incision. (b) Osteochondral fragment provisionally fixed with K-wire. (c) Fragment fixed with Herbert screw.

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Post-operative radiograph confirmed adequate screw placement [Figure 4a]. Postoperatively, the patient was kept non-weight-bearing for 4 weeks, followed by partial weight bearing for 6 weeks, and then progressed to full weight bearing. This protected the meniscus repair and allowed the osteochondral fragment to heal. Knee ROM exercises were started at 2 weeks, gradually reaching 90° by 4 weeks and full ROM by 6 weeks. Early ROM was encouraged to prevent stiffness, while progression was controlled to avoid stress on the fixation. A knee immobilizer was applied for the first 6 weeks, followed by a hinged brace for another 6 weeks to support the transition. By 6 weeks, the patient reported no pain or instability.

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Figure 4:

(a) Post-operative radiograph showing adequate screw placement (blue arrow) and anterior cruciate ligament with anterolateral ligament reconstruction. (b) Six-month post-operative magnetic resonance imaging showing healing of the osteochondral fragment (yellow arrow). (c) Healing of osteochondral fragment with Herbert screw in situ. (d) Cartilage injury on the medial tibial condyle (yellow arrow) with a healed posterior horn of the medial meniscus (blue arrow).

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At 6 months, MRI imaging confirmed healing of the osteochondral fragment [Figure 4b]. Due to the presence of a metallic implant, implant removal was advised. Arthroscopic evaluation at the time of removal confirmed successful healing of the osteochondral fragment [Figure 4c] and meniscus repair. There was a grade 2 cartilage injury on the medial tibial condyle [Figure 4d], likely caused by the hardware contact. A mini-open approach was used at the previous incision site, and the Herbert screw was removed [Figure 5].

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Figure 5:

Postoperative anteroposterior and lateral radiograph of the right knee after screw removal.

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After implant removal, the patient immediately started full weight-bearing and full knee ROM exercises. Sports-specific rehabilitation was initiated, focusing on strength and proprioception. At 1 year postoperatively, the patient had excellent functional outcomes [Figure 6], with clinical scores as follows:

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Figure 6:

Clinical outcomes showing full knee range of motion (flexion and extension).

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• ACL-RSI: 90

• Tegner Lysholm Knee Score: 95

• SKV: 95

• IKDC Score: 85

• KOOS: 95

At 2 years’ follow-up, the patient reported no pain or instability, with full return to sports and daily activities.

DISCUSSION

Osteochondral injuries of the MFC are rare in ACL injuries, as the typical injury mechanism involves valgus stress with internal rotation, resulting in LFC impaction against the posterior tibial plateau.^[2] This commonly leads to bone bruises or LFC osteochondral fractures, often seen as the femoral notch sign.^[3] In contrast, MFC lesions, though uncommon, may arise through a countercoup mechanism during pivot-shift injuries, where lateral impact is followed by secondary medial compression, sometimes accentuated by hyperextension. When such fractures do occur, as in our case, they are distinctly uncommon and require a tailored fixation strategy, particularly in the weight-bearing region. Fragment viability is important for successful fixation because only intact cartilage with preserved structure can integrate and heal effectively. Early fixation (within 2 weeks) is preferred for optimal outcomes.^[4] In our case, the patient presented to us 10 days post-injury after initial conservative care elsewhere, and an MRI was obtained at first evaluation. While earlier imaging might have detected the lesion sooner, the fragment was viable and fixed within this window, which supported good healing.

There are various fixation methods for osteochondral fractures, each with its advantages and limitations based on fragment size, location, and stability requirements.

Herbert screws are commonly used for rigid fixation, particularly in weight-bearing zones. Herbert screws offer strong fixation but have some limitations. They are a good option when the fragment is large and thick enough to hold the threads securely in place. Very small or thin fragments may crack during insertion. In cases where the lesions are in curved or hard-to-reach areas of the condyle, it is difficult to get the right angle for stable fixation. This makes careful planning important before deciding on this technique. Agarwala et al.^[5] reported successful fixation and anatomic reduction of an LFC osteochondral fracture with Herbert screws using a Z-plasty approach. However, implant removal was done post-healing due to hardware prominence. Sharma et al.^[3] described Herbert screw fixation for a displaced LFC osteochondral fragment associated with an ACL avulsion fracture. They highlighted the importance of early fixation to prevent cartilage degradation. In this case, Herbert screw fixation provides adequate stability with minimal cartilage damage on the medial tibial condyle due to the implant. This approach permitted early rehabilitation and successful fragment healing, similar to previously reported outcomes, making them more suitable than other contemporary arthroscopic fixation devices in this setting.

Bioabsorbable pins offer the advantage of eliminating the need for implant removal. Walsh et al.^[6] described the use of bioabsorbable pins for LFC osteochondral fractures, which achieves stable fixation as well as avoids secondary surgery. However, slow degradation, subchondral cyst formation, and inflammatory reactions were noted, particularly in weight-bearing regions, making them less favorable for MFC fixation. Compared to bioabsorbable pins, the Herbert screw fixation used in our case ensured rigid compression, minimizing the risk of fragment displacement and secondary complications. Suture-based fixation techniques, like suture bridges, provide fragment stabilization without damaging the cartilage surface. Vogel et al.^[4] reported a fragment-preserving suture technique, highlighting its ability to minimize cartilage damage. However, it was noted that this technique offers limited stability, especially for large, weight-bearing fragments seen in MFC injuries. Similarly, Bowers and Huffman^[7] described a suture bridge technique for femoral condyle fractures, ensuring compression without cartilage violation. This technique is effective for non-weight-bearing zones, but it is technically demanding and less suited for MFC lesions, which require rigid fixation. In contrast, Herbert screw fixation provided strong compression, making it more appropriate for the medial weight-bearing region.

Suture anchor fixation is another minimally invasive approach for osteochondral fixation. Huang et al.^[8] reported the use of a single suture anchor for in situ fixation of weight-bearing osteochondral fragments, emphasizing its simplicity and cost-effectiveness. However, anchor-based fixation lacks sufficient compression for large, weight-bearing fragments, as observed in MFC injuries. Compared to suture anchors, the Herbert screw fixation in our case offered superior compression and stability, ensuring successful healing without fragment migration.

Autologous chondrocyte implantation (ACI) and matrix-assisted chondrocyte implantation can be used for large osteochondral defects. Kaibara et al.^[9] treated an LFC osteochondral defect using atelocollagen, ACI, and bone graft with a good functional outcome. While ACI offers favorable outcomes, it requires multiple stages, higher costs, and prolonged rehabilitation, making it less suitable for acute traumatic cases like ours. In contrast, Herbert screw fixation provided a single-stage solution, enabling early mobilization and return to sport.

CONCLUSION

Osteochondral fractures of the MFC in ACL injuries are a unique presentation. While bioabsorbable pins, suture anchors, and ACI offer viable solutions, they have their limitations, especially in weight-bearing zones. Our approach of arthroscopically harvesting the osteochondral fragment, followed by mini-open Herbert screw fixation, provided rigid fixation, anatomical reduction, and successful rehabilitation, making it a reliable alternative for rare MFC osteochondral injuries. Long-term outcome evaluations and comparative trials will be essential to refine surgical strategies and improve clinical success for similar cases.