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The Segond fracture is commonly regarded as pathognomonic for significant intra-articular pathology such as an anterior cruciate ligament (ACL) tear. There is worsened rotatory instability in patients with concomitant ACL tear and Segond fracture. Current evidence does not suggest that a concomitant and unrepaired Segond fracture leads to worst clinical outcomes after ACL reconstruction. However, there remains a lack of consensus on several aspects of the Segond fracture such as its exact anatomical attachments, ideal imaging modality for detection and indication for surgical treatment. There is currently no comparative study evaluating the outcomes of combined ACL reconstruction and Segond fracture fixation. More research is necessary to deepen our understanding and establish consensus on the role of surgical intervention.
The Segond fracture was first described in 1879 by Dr Paul Segond as an avulsion fracture occurring at the anterolateral aspect of the tibia plateau – arising from forced internal rotation of the knee.
However, the clinical significance of the Segond fracture remains uncertain. Currently, there is a lack of established consensus regarding the need for surgical fixation of the fracture.
Establishing clear guidelines on Segond fracture treatment is necessary. There are many controversies regarding the Segond fracture. Firstly, the exact anatomic origin of fracture is currently debated. Whilst the original description was a “pearly white fibrous band”, the posterior fibres of the iliotibial band, mid-third of the lateral capsular ligament, and the anterolateral ligament (ALL) are all considered to contribute to the formation of the Segond fracture. Secondly, whilst the Segond fracture has been shown to worsen the pivot-shift mechanism following an ACL injury,
it is uncertain if this worsens clinical rotational instability, or if fixation of Segond fracture in addition to ACL reconstruction will improve stability. This is compounded by the possibility of spontaneous Segond fracture healing.
In addition to the lack of understanding of its anatomy and biomechanical implications, there is also no consensus regarding the ideal surgical treatment, which may either be direct Segond fracture fixation or anatomical ALL reconstruction.
It is clear that a multi-faceted understanding of the anatomical, biomechanical and clinical aspects of the Segond fracture is necessary to elucidate its clinical role and the need for intervention. This paper aims to illustrate how our knowledge of this entity has evolved, and to highlight the existing controversies and areas where research is progressing.
1.2 Prevalence and demographics
The prevalence of the Segond fracture ranges from 2.4% to 9% of patients with ACL tears.
In a systematic review of 5 studies comprising 2418 patients including 304 Segond fractures, the mean age of patients with Segond fracture was 28.1 years with a male proportion of 64.1%.
However, there is no gender or age predilection for the occurrence of a Segond fracture. The demographic of patients who had a Segond fracture and/or a healed Segond fracture was similar to patients with isolated ACL injury in terms of age (Segond fracture with ACL: 30 ± 11 years vs isolated ACL: 28 ± 10 years), male proportion (Segond fracture with ACL: 58% vs isolated ACL: 54%) and laterality of injury (Segond fracture with ACL: 43% left knee and 57% right knee, vs isolated ACL: 49% left knee and 51% right knee).
The size of the fragment can vary. In a study of the radiographic and magnetic resonance imaging (MRI) features of 36 patients with combined ACL injury and Segond fracture, the fracture fragment had a mean proximal-distal length of 9.2 mm on plain radiograph and 8.7 mm on MRI, and measured a mean distance between the mid-point of the avulsed fracture fragment to the tibial plateau edge of 4.6 mm on plain radiographs and 7.8 mm on MRI.
however, its specific anatomical attachments are less well understood. In 1879, Dr Paul Segond discovered a “pearly, resistant, articular fibrous band, which in the exaggeration of internal rotation, suffers an extreme degree of tension”.
This “band” caused significant traction on its insertion point, leading to a constant fracture pattern at the proximolateral tibia – immediately behind the Gerdy's tubercle – known as the Segond fracture today. Prominent cadaveric studies in the next century continued to advance our understanding on the anatomy of the Segond fracture. Various studies have postulated that the identity of the “pearly fibrous band” could be the ITB,
Radiological findings complement the principles derived from cadaveric studies. In 1936, Milch reported a constant Segond fracture pattern seen on plain radiographs and referenced Dr Paul Segond's work to explain his findings.
A study showed that there were no statistically significant differences between the location of the ALL avulsion and the Segond fracture – with a mean gerdy tubercle-ALL distance of 22.0 ± 4.0 mm on cadaveric dissection, matching the mean gerdy tubercle-Segond distance of 22.4 ± 2.6 mm on MRI.
This strengthened the belief that the Segond fracture is closely associated with the ALL.
Despite numerous studies, the identity of the “pearly fibrous band” continues to remain an enigma today. Sonnery-Cottet and the ALL Expert Group concluded in 2017 that the ALL attaches posterior and proximal to the lateral epicondyle of the femur, with distal attachments at the anterolateral tibia between the Gerdy's tubercle and the fibular head (Fig. 3.).
Anterolateral Ligament Expert Group consensus paper on the management of internal rotation and instability of the anterior cruciate ligament - deficient knee.
The Segond fracture was thought to represent an avulsion injury of the tibial insertion of the ALL caused by high tension forces during internal rotation and varus stress of the knee. However, Shaikh et al. (2017) found that whilst the fracture occurred in the reported tibial insertion of the ALL, MRI analysis found that the “anterolateral complex” comprising of the posterior fibres of the ITB and the lateral capsule were attached to the Segond fracture in 94% of patients.
These attachments were found with either isolated meniscotibial component of the mid-third lateral capsular ligament attachment in 58.9% (86/146) of patients, or combined attachment of the meniscotibial component of the mid-third lateral capsular ligament and posterior fibres of the ITB in 35.6% (52/146) of patients.
The literature remains divided on the exact structure responsible for the Segond fracture. The proposed possibilities include the ALL or an anterolateral complex, comprising of the ITB,
Further anatomical investigations are necessary to deepen our understanding of the anatomy of the Segond fracture.
2.2 Associated injuries
The Segond fracture is associated with significant intra- and peri-articular knee pathology (Table 1.). Radiological studies of patients with Segond fractures showed associated torn or absent ACL in 100% (9/9) of patients, posterior cruciate ligament (PCL) tear in 11.1% (1/9) of patients, lateral capsular damage in 44.4% (4/9) of patients, meniscal tear in 66.7% (6/9) of patients, osteochondral defect of the anterior lateral femoral condyle in 44.4% (4/9) of patients, ITB avulsion at the Gerdy tubercle insertion in 44.4% (4/9) of patients and avulsion of the fibular collateral ligament at the fibular head insertion in 44.4% (4/9) of patients.
In a clinical study by Yeo et al. of patients with concurrent Segond fracture and ACL injury, associated lateral meniscal tears were most commonly detected by MRI in 60.0% (6/10) of patients followed by medial meniscus tears in 20.0% (2/10) of patients.
Associated ACL injuries is the most well studied. An average incidence of 10.5% of concomitant Segond fracture were found in patients with ACL injuries in 6 studies.
They also showed that a higher percentage (32%) of Segond fracture was sustained during low-risk pivoting sports such as running and skiing, as compared that those sustained from high-risk pivoting sports (28%) including soccer and basketball.
It is hypothesised that direct force from the anterolateral aspect to the posterior aspect of the knee, with likely varus and twisting forces caused the Segond fracture with the PCL tear.
This was reported in cases of patients falling off a bicycle at high speed, or falling at running speed, where there was direct impact on the anterolateral aspect of the knee.
The association of Segond fractures with medial collateral ligament (MCL) injuries may be related to excess valgus movement of the knee, although it is uncommon.
It was described that a high-speed impact to the lateral aspect of the knee causing a valgus deformity may explain MCL injury in cases of Segond fractures.
A study showed that there was a higher incidence of lateral meniscus tear in patients with Segond fractures (49.1%) as compared to those without (32.6%).
The higher incidence of lateral meniscus tear may be a result of higher stress produced from the femoral condyle during internal rotation of the knee in flexion.
In a study of 53 paediatric and adolescent patients with Segond fractures, Kushare et al. found that 73.6% (39/53) of patients had ACL tears, 17.0% (9/53) of patients had tibial spine fractures, 69.8% (37/53) of patients had meniscal injury and 5.7% (3/53) had multi-ligamentous injuries.
Thus, it is important to have a high index of suspicion for other significant intra- and peri-articular injuries when a Segond Fracture is detected regardless of the patients’ age groups. Whilst ACL lesions remain the most commonly associated, other injuries such as meniscus, lateral capsular or ITB injuries should be considered.
2.3 Imaging modalities
Plain radiography has been considered to be the gold standard in detecting Segond fractures (Fig. 1A).
However, the use of newer imaging modalities – such as MRI (Fig. 1B) – has shown increased incidence rates that differ from the existing literature. Employing the use of ultrasonography (US), Klos et al. (2017) detected concomitant Segond fracture in 29% (25/87) of patients with ACL injury.
Similarly, Cavaignac et al. (2017) detected Segond fractures amongst patients with ACL injury in 50% (15/30) of patients using US – three-folds the detection rate of 13% (4/30) using MRI in the same study.
This suggests that the diagnostic rates for Segond fractures are lower on plain radiography as compared to advanced imaging modalities. This was demonstrated by Kumahara et al. (2022) in a series of 540 patients undergoing primary ACL reconstruction. They found an incidence rate of concomitant Segond fracture in 3.3% (18/540) of patients using plain radiographs, in 3.7% (20/540) of patients using MRI, and in 4.1% (22/540) of patients using computed tomography (CT).
Further comparative studies are needed to identify the optimal imaging modality for detection for a Segond fracture. Given the current evidence, we recommend that Segond fractures should be assessed for not only on plain radiography, but also on advanced imaging modalities such as US, CT or MRI.
Fig. 1Segond fracture visualized on different imaging modalities.Left figure: Anterior-posterior radiograph of the left knee demonstrating a Segond fracture (arrow) visualized as a thin, curvilinear bony fragment adjacent to the lateral aspect of the proximal tibial plateau. Right figure: Coronal proton density-weighted magnetic resonance sequence of a right knee, demonstrating an undisplaced Segond fragment (arrowhead) in the same location.
Hess et al. described a consistent mechanism of injury of knee flexion and internal rotation of the tibia on the femur, in patients with ACL injuries and concomitant Segond fractures.
This mechanism of injury often occurs in sports such as football and downhill skiing as these sports frequently involve excessive pivoting on one limb with force.
A study of 1364 patients with 207 recent and healed Segond fractures reported that the most common events leading to the Segond fracture were downhill skating (44.6%), skiing (14.9%) and team handball (11.8%).
The same study also showed that the distribution of events were similar to those that led to isolated ACL injury (soccer 40.6%, downhill skiing 24.8%, team handball 7.9%).
However, there was a statistically significant predisposition for Segond fracture amongst patients injured during downhill skiing, attributed to the combination of high energy and sudden rapid change in force vectors during such activity. In summary, there appears to be a higher risk of developing Segond fracture in high energy sports such as downhill skiing. However, there is no specific sporting activity that has been associated with this injury.
3.2 Biomechanical features
The Segond fracture results in increased rotational instability, particularly in mid-knee flexion.
A biomechanical study of 7 cadaveric knees subjected to step-wise dissection replicating three states (intact knee, ACL-deficient knee, and ACL-deficient knee with Segond fracture) found that knees with Segond fracture and concurrent ACL injury caused a significant increase in rotational laxity (mean axial tibial rotation (ATR): 19.1 ± 3.1°) as compared to knees with isolated ACL injury (mean ATR: 12.3 ± 2.3°) and the intact knee (mean ATR: 9.6 ± 1.8°).
This increased laxity was more pronounced at 30° flexion of the knee – ACL injuries with concomitant Segond fractures showed a mean ATR of 30.9 ± 3.8°. It is suggested that rotational instability may be due to other injuries concurrent to ACL tears, and not merely due to ACL lesions alone.
Results of instability from cadaveric studies have not been consistently demonstrated in human studies. Melugin et al. (2018) compared the joint laxity scores of patients with concomitant ACL injury and Segond fracture to patients with isolated ACL injury discovered significantly worst anteroposterior instability based on Lachman test scores, and rotational instability based on Pivot-shift test scores amongst pre-operative patients.
However, the authors reported no statistically significant differences in joint laxity score between the two groups post-operatively. In comparison, difference in pre-operative Lachman test score and Pivot-shift test score was not seen in Yoon et al.‘s (2018) study,
although lack of post-operative difference was similarly observed. The presence of rotational instability with an exaggerated pivot-shift mechanism may be a sign of concomitant Segond fracture in the context of ACL injury.
4. Clinical implications
There is a lack of evidence to support surgical fixation of Segond fractures. To the best of the authors’ knowledge, there is no study to date that directly compares the post-operative outcomes of patients with concomitant Segond fracture fixation with ACL reconstruction, against patients with unrepaired Segond fracture. Few studies have analysed the clinical benefits of Segond fracture fixation. A case report of concomitant ACL reconstruction and Segond fracture fixation using Vicryl figure-of-8 sutures by Albers et al. (2018) showed improvements in post-operative Lachman and Pivot-shift test scores.
Fernandes et al. (2018) similarly reported a case of concomitant ACL reconstruction and Segond fracture fixation using 3.5 mm cancellous screw and washer with improvements of joint laxity scores in some patients post-operatively.
The largest of such studies was published by Ferretti et al. (2017), who performed concomitant ACL reconstruction and Segond fracture fixation in 12 patients.
They employed a size-based algorithm for choosing Segond fragment fixation technique (Fig. 2) – either direct suture (3 parallel square knot stitches using 2-0 Vicryl suture) (7 cases) or anchor fixation (5-mm suture anchor with mattress suture fixation) (4 cases) when fragment was 2 cm2 or smaller, and cannulated screw fixation when fragment was larger than 2 cm2 (1 case). They found statistically significantly improved post-operative scores compared to pre-operative scores based on the Lysholm, Tegner and International Knee Documentation Committee (IKDC) subjective scores.
: For fragments 2 cm2 or smaller, either periosteal suture fixation (left figure), or suture anchor fixation (middle figure) was employed. For fragments larger than 2 cm2, cannulated screw fixation (right figure) was used.
Fig. 3The anterolateral ligament (ALL). The ALL originates posterior and proximal to the lateral epicondyle of the femur. It overlaps the LCL proximally as it travels distally to attach to the proximal tibia, just posterior to Gerdy's tubercle. It also gives off fibres that attach to the lateral meniscus.
Anterolateral Ligament Expert Group consensus paper on the management of internal rotation and instability of the anterior cruciate ligament - deficient knee.
Most studies in the current literature have compared the post-operative outcomes of patients with unrepaired Segond fracture undergoing ACL reconstruction, against patients undergoing ACL reconstruction without the fracture. Most recently, Nagai et al. (2021) published a systematic review with 4 studies that compared the outcomes of patients with ACL reconstruction with unrepaired Segond fracture against those with isolated ACL reconstruction, and 1 study on the outcomes of patients undergoing concomitant ACL reconstruction and Segond fracture repair.
reported no significant difference in Tegner activity scale score between patients with and without Segond fracture. One study reported no significant difference in mean Lysholm score between the two groups.
Mixed results were observed across studies that compared subjective IKDC score, whereas 1 study of reported lower post-operative scores amongst patients with Segond fracture,
the mean difference in the former study was 6.5 and was therefore concluded to be not clinically relevant (Table 2).
Nagai et al. (2021) further performed a meta-analysis comparing graft failures between patients with unrepaired Segond fracture and patients without the fracture.
Their analysis showed a cumulative graft failure rate of 3.8% in patients with unrepaired Segond fracture, and 6.9% in patients without Segond fracture.
Statistically, there was no significant difference in the risk of graft failure between the 2 cohorts, with a pooled risk ratio of 0.59 (95% CI: 0.32–1.07, P = 0.08, I2 = 0%).
Overall, the results of Nagai et al.‘s (2021) systematic review suggest that post-operative clinical outcomes amongst patients with concomitant ACL reconstruction with Segond fracture repair showed statistically insignificant improved outcomes as compared with patients who underwent Segond fracture alone.
Graft failure rate amongst cases with concomitant ACL injury and unrepaired Segond fracture is comparable to those with isolated ACL injury. The authors concluded that concomitant Segond fracture fixation is not required with ACL reconstruction. One plausible explanation for this was the observed phenomenon of spontaneous Segond fracture healing. In the same systematic review, there were 3 included studies that assessed for spontaneous healing of the Segond fracture without surgical intervention using post-operative radiographs. Two studies reported a 90% healing rate, while 1 study reported a 35.6% healing rate.
It could be hypothesised that spontaneous healing of the fracture fragment at that time of patient review led to a lack of difference in post-operative joint laxity and clinical outcome score.
It is possible that undetected or healed Segond fractures were present in the control groups given the difference in detection rate between different imaging modalities. Amongst the 5 included studies, 3 used radiographs for the majority of their sample population
Furthermore, there may be other forms of ALL injury with undetected Segond fracture (healed or otherwise) potentially confounding the clinical outcome of graft failure rate data. This could explain the lack of significant difference in outcomes between groups as observed across the different studies. Finally, the effect of un-fixed Segond fractures and potential worsened rotational instability on long term clinical outcomes and risk of secondary osteoarthritis is unclear.
There is currently no evidence to suggest that concomitant Segond fracture fixation with ACL reconstruction improves clinical outcomes. Clearly, further robust studies are required with regards to the need for Segond fracture fixation. In designing future studies, authors should document the presence of other forms of ALL injuries and healed Segond fracture in study groups. US, CT or MRI should be routinely performed to detect Segond fractures or its associated injuries. Additionally, given that spontaneous osseous healing has been observed on follow-up, the description of short-, intermediate- and long-term outcome measures will enable a deeper understanding of the effects of a concomitant Segond fracture.
5. Conclusion
The understanding of the anatomical, biomechanical and clinical features of the Segond fracture continues to improve. There is a lack of consensus on the exact anatomical attachments of the Segond fracture fragment. With regards surgical treatment of the Segond fracture, the current evidence suggests that a concomitant, unrepaired Segond fracture does not result in worst outcomes following ACL reconstruction.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
References
Segond P.
Recherches cliniques et expérimentales sur les épanchements sanguins du genou par entorse. Aux Bureaux du Progrès medical.
Anterolateral Ligament Expert Group consensus paper on the management of internal rotation and instability of the anterior cruciate ligament - deficient knee.
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