Comprehensive classification and its value of capitellar cartilage injury concomitant with radial head fracture

Abstract

Background

There are defects in the existing classification of capitellar cartilage injury (CCI) concomitant with radial head fracture (RHF). This study aimed to introduce a comprehensive classification of CCI and to analyze its surgical guidance value.

Methods

According to the affected site and severity, CCI was classified into four types: Type I - partial-thickness loss of articular cartilage, Type II - full-thickness loss of articular cartilage, Type III - full-thickness loss of articular cartilage with subchondral bone loss, Type IV - full-thickness loss of articular cartilage with thin cortex loss on the border of the capitellum; Different types suggest different surgical methods. Between January 2017 and January 2023, this comprehensive CCI classification was applied in 31 operated patients with CCI concomitant with RHF. The ranges of motion (ROM), Mayo Elbow Performance Index (MEPI) score, Hospital for Special Surgery (HSS) score and visual analog scale (VAS) for pain, were used to evaluate the functional recovery of the affected limb.

Results

Mason Type I-IV RHF accounted for 6.45%, 38.71%, 48.39%, and 6.45%, respectively. Type I-IV CCI accounted for 12.90%, 35.48%, 45.16% and 6.45%, respectively. There was no relationship between the CCI and RHF types (p > 0.05). At the end of the follow-up period of 11–26 months with an average of 16 months, the elbow flexion and extension ROM recovered to (147.39 ± 9.84)°, forearm rotation ROM recovered to (168.74 ± 11.70)°, MEPI score recovered to (89.19 ± 4.17), HSS score recovered to (88.74 ± 4.62), VAS score recovered to (0.50 ± 0.57), indicating significant differences compared to preoperative measurements (p < 0.05). According to the MEPI and HSS scores, the excellent and good rate of functional recovery was 100%.

Conclusion

Different types of CCI differ not only in pathology but also in treatment methods. Surgical strategy according to the comprehensive CCI classification introduced in this paper may lead to a satisfactory outcome.

Introduction

Radial head fracture (RHF) accounts for one-third of elbow fractures [1, 2], and is typically caused by axial loads in the extended or semi flexed position of the elbow, as well as impacts on the radial head and capitellum, or supine and eversion loads in the medial rotation position (posterior lateral rotation) of the forearm after a fall. The incidence of RHF-associated elbow ligament, bone, the and cartilage injuries is high ranging from 30 to 77% [3–5]. Among them, the incidence of the capitellar cartilage injury (CCI) concomitant with RHF is 23–39%, and it is prone to missed diagnosis [4, 6–12]. Missed CCI can lead to complications such as avascular necrosis, malunion, nonunion, and loss of elbow function [11–13]. Most scholars [4–6] classified CCI into Types I (partial-thickness loss of articular cartilage) and Type II (full-thickness loss of articular cartilage). However, in clinical practice, there are also cases of full-thickness articular cartilage loss accompanied by subchondral bone loss or boundary thin cortex of the capitellum, which have different surgical treatment methods. Hence, there are defects in the existing classification of CCI, it has limited guidance value for surgery. Good classification helps communicate and guide treatment [14]. To fill this gap, this study aimed to introduce a new CCI classification and to analyze its application effectiveness.

Materials and methods

Comprehensive CCI classification and surgical guidance

According to the affected sites and severity, CCI was categorized into four types: Type I - partial-thickness loss of articular cartilage; Type II -full-thickness loss of articular cartilage; Type III- full-thickness loss of articular cartilage with local subchondral bone loss; Type IV- full-thickness loss of articular cartilage with thin cortex loss on the border of the capitellum. Figure 1.

Fig. 1.

Diagram for comprehensive CCI classification

For Type I, excision is the only correct treatment method. For Type II and Type III, they can be excised or fixed depending on the size and comminution. Small or comminuted cartilage fragments that are difficult to fix can be removed, while large cartilage fragments can be fixed through cartilage using suture anchors or headless screws. Type II requires microfracture repair while Type III does not. For Type IV, screws used for fixation through cortical bone.

General information

This prospective study was approved by the ethics review committee of our hospitals (No. KT2017026 and NO. YC2017101, registration date: January 14, 2017), and performed in accordance with the ethical standards established in the 1964 Declaration of Helsinki and its later amendments. Written informed consent was obtained from the participant’s parent/guardian or legally authorized representative for the participant of age 15–18. Inclusion criteria: (1) Patients with RHF surgically treated at our hospital between January 2017 and January 2023; (2) CCI was detected or confirmed during surgery. Exclusion criteria were as follows: (1) open elbow fractures caused by direct trauma; (2) patients with elbow diseases or surgery before injury; (3) follow-up duration < 10 months; and (4) incomplete imaging and clinical data.

A total of 130 cases with RHF were screened, 35 cases of CCI concomitant with RHF met the inclusion criterion, 4 cases were excluded according to the exclusion criteria, 31 cases were included in the study. There were 19 males and 12 females; aged 15 to 75 years, with an average age of 39.7 years. The causes of injury included falls (22 cases), fall-from-height injuries (2 cases), sports injuries (6 cases), and other cause (1 case). Associated medial or lateral collateral ligament complex injuries occurred in 18 cases and associated avulsion fracture occurred in 2 cases. All patients received X-ray and CT examinations, 22 of whom underwent MRI. The diagnosis rate of CCI by radiology was 16.13%, including 3 cases of Type III and 2 cases of Type IV. Causes of surgery: 28 cases due to severe RHF, and 3 cases due to relative mild RHF but obviously restricted rotation, indicating mechanical blockage; Surgical methods: ORIF in 27 cases and arthroscopically assisted reduction and internal fixation in 4 cases.

Observation methods

According to the Mason classification, RHF was categorized into four types of severity: Type I (fractures with no displacement of the radial head or neck or with displacement of less than 2 mm), Type II (fractures with displacement exceeding 2 mm), Type III (comminuted fracture), and Type IV (RHF with elbow instability, including ulnar coracoid process fracture, medial and lateral collateral ligament complex injury, and elbow dislocation). The ranges of motion (ROM) of the elbow were given attention. The Mayo Elbow Performance Index (MEPI) score, Hospital for Special Surgery (HSS) score [15] and visual analog scale (VAS) for pain were used to evaluate preoperative and postoperative elbow function.

Statistical analysis

Statistical analysis was performed in SPSS 25.0 (SPSS Inc., USA). We compared the preoperative and postoperative functions. The Shapiro‒Wilk test was used to test the normality of the measurement data. Measurement data following a normal distribution are expressed as ± s, and those with a nonnormal distribution are expressed as M(Q25–Q75). A paired sample t-test was used when the data followed a normal distribution, and the Frank Wilcoxon test was used when the data did not conform to a normal distribution. When analyzing the relationship between CCI type and RHF type, a chi2 test was used. P < 0.05 was statistically significant.

Results

Patients with Mason Type I, II, III, and IV RHF accounted for 6.45%, 38.71%, 48.39%, and 6.45%, respectively. Patients with Type I, II, III and IV CCI accounted for 12.90%, 35.48%, 45.16% and 6.45%, respectively. The RHF and CCI classification results are shown in Table 1, and no obvious relationship was observed between the CCI and RHF types (p > 0.05). They were followed up 11–26 months with an average of 16 months. At the last follow-up, the ROM of elbow flexion and extension was recovered to (147.39 ± 9.84)°, the ROM of forearm rotation recovered to (168.74 ± 11.70)°, the MEPI score recovered to (89.19 ± 4.17), the HSS score recovered to (88.74 ± 4.62), and the VAS score was recovered to (0.52 ± 0.57), with significant differences compared to preoperative measurements (p < 0.05). Table 2. The excellent and good rate of functional recovery was 100% based on MEPI and HSS scores. Typical cases are shown in Figs. 2, 3, 4 and 5.

Table 1.

RHF and CCI classification results

Mason of RHF	Type I of CCI (4)	Type II of CCI (11)	Type III of CCI (14)	Type IV of CCI (2)
Type I (2)		1	1
Type II (12)	2	4	5	1
Type III (15)	2	5	7	1
Type IV (2)		1	1

Table 2.

Treatment results

Measurements	Preoperative	Postoperative	Statistics	P
Flection-extention ROM	74.00 ± 11.03	147.39 ± 9.84	37.382	< 0.001
Rotation ROM	89.45 ± 8.29	168.74 ± 11.70	30.415	< 0.001
MEPI score	53.39 ± 6.88	89.19 ± 4.17	33.831	< 0.001
HSS score	62.97 ± 6.57	88.74 ± 4.62	18.228	< 0.001
VAS	5.03 ± 0.98	0.52 ± 0.57	25.254	< 0.001

Fig. 2.

A 50-year-old male with right RHF and CCI. (a, b) Preoperative X-ray radiographs showed RHF. (c) Preoperative CT showed Mason Type II RHF. (d) Intraoperative exploration of arthroscopically assisted surgery showed Mason Type II RHF with Type I CCI (blue arrow). (e, f) X-ray radiographs at 3 months after surgery showed fracture healing. (g-i) The appearance of the affected limb with excellent function 1 year after surgery

Fig. 3.

A 51-year-old female with left RHF and CCI. (a, b) Preoperative X-ray radiographs showed RHF. (c) Preoperative CT showed Mason Type II RHF. (d) Preoperative MRI showed RHF with lateral collateral ligament injury without CCI. (e) Intraoperative exploration showed RHF with Type II CCI (blue arrow). (f, g) X-ray radiographs at 3 months after surgery showed fracture healing. (h-j) The functional recovery and appearance of the affected limb were excellent 15 months after surgery

Fig. 4.

A 65-year-old female with left RHF and CCI. (a, b) Preoperative X-ray radiographs showed RHF. (c) Preoperative CT showed Mason Type II RHF. (d, e) Preoperative MRI showed RHF with CCI. (f) Intraoperative exploration showed RHF with Type III CCI (blue arrow). (g, h) X-ray radiographs at 3 months after surgery showed fracture healing. (i-k) The appearance of functional recovery of the affected limb was evaluated as good 1 year after surgery

Fig. 5.

A 28-year-old male with left RHF and CCI. (a, b) Preoperative anteroposterior and lateral X-ray radiographs showed left RHF with CCI. (c) Preoperative sagittal CT scan showed left Mason Type II RHF with Type IV CCI. (d) Intraoperative exploration showed RHF with Type IV CCI (blue arrow). (e, f) The anteroposterior and lateral X-ray radiographs 3 months after surgery showed good fracture alignment and bone healing. (g-i) The functional appearance 15 months after surgery

Discussion

Incidence and diagnosis of CCI

Itamura J et al. [12] reported 24 cases of RHF and found CCI concomitant with RHF in 7 (29%) of these patients by MRI. A systematic MRI examination of 46 RHFs by Kaas L [4] was able to detect CCI in 39% of cases. In this study, the incidence rate of CCI concomitant with RHF was 26.9%, similar to the reports in the literature.

Except Type IV, Types I-III CCI only involve limited articular cartilage or/and subchondral bone, and usually are not evident on X-ray, CT and even MRI. Harbrecht et al. [16] reported 4 case with CCI concomitant with RHF, none of them showed evidence of CCI preoperatively, all were confirmed upon surgery. Nalbantoglu U et al. [6] reported only one of 10 cases with CCI concomitant with RHF was identified by X-ray and CT before operation, his CCI was Type IV according to our classification, i.e., the diagnosis rate of CCI was 10%. In this study, the diagnosis rate of CCI by radiology was 16.13%, and 22.58% by radiology and clinical physical examination, among them, and the diagnosis rate of Type I-III CCI was 10.71%. Therefore, the high missed diagnosis rate of CCI is a major clinical feature of CCI concomitant with RHF [17–19].

Because the cartilage fragments of CCI are often interposed in the joint space and/or the fracture gap of RHF, the patients have substantially limited movement, especially of forearm rotation. Park et al. [18] revealed that obviously limited forearm rotation indicates mechanical blockage and possibility of CCI, that requires surgery. In this study, 2 cases with Mason Type I RHF had obviously limited forearm rotation were operated through arthroscopically assisted reduction and internal fixation, and CCI concomitant with RHF was found upon surgery. Therefore, we support Park’s above viewpoint.

Basis for CCI classification and surgical guidance

Nalbantoglu U et al. [6] divided CCI into Types I and II, they did not distinguish full-thickness loss of articular cartilage and full-thickness loss of articular cartilage with local subchondral bone loss, which we refer to as Type II and Type III. They [6] also found the presence of full-thickness loss of articular cartilage with thin border cortex loss, but they did not distinguish it from partial and full-thickness loss of articular cartilage, we assign it to as Types IV, similar to Graham’s [20] Type I capitellar fracture, which can usually be diagnosed through X-ray examination and CT. Type I CCI cannot be repaired, removal is the only treatment method. Type III involves subchondral trabecular bone loss, so microfracture repair is not necessary, whereas type II CCI does not involve subchondral trabecular bone loss, so microfracture repair is necessary. Microfracture repair helps to form granulation tissue and fibrosis, providing alternative repair for cartilage defects [21, 22]. Therefore, distinguishing Type II and Type III is necessary. Due to cortex fracture occurring on the border of capitellum, cortex fixation using screw is the preferred choice for Type IV CCI. In summary, Types I-IV CCI differ not only in pathology but also in treatment methods.

Treatment effectiveness

Harbrecht et al. [16] reported 4 cases with CCI concomitant with RHF, the CCI fragments were removed and the RHFs were treated with ORIF, all fractures healed, with excellent function and low pain scores in all patients at mean follow-up of 9.25 months. Park et al. [18] reported 12 cases with CCI concomitant with RHF, 9 excellent and 3 good results at the mean follow-up period was 21.3 (16–28) months. In this study, the elbow functional recovery was rated as excellent and good rate in 100% of patients based on MEPI at 16 months followed up, i.e. the surgical strategy according to comprehensive CCI classification leaded to a satisfactory postoperative outcome.

There are some limitations in this study. First, this is a retrospective single center study. Second, “second-look operation” or MRI was not performed at the final follow-up. Therefore, it was difficult to identify the final status of the CCI. However, The comprehensive CCI classification introduced in this study is comprehensive and can provide good reference for surgical methods.

Conclusions

Different types of CCI differ not only in pathology but also in treatment methods. Surgical strategy according to the comprehensive CCI classification introduced in this paper may lead to a satisfactory postoperative outcome.

Abbreviations

RHF

Radial head fracture

CCI

capitellar cartilage injury

MEPI

Mayo elbow performance index

HSS

Hospital for special surgery

VAS

Visual analog scale

Author contributions

HX B, XF S and HF L wrote the initial draft of this manuscript and subsequent revisions. GY Z, ZC C, XF S and YP D prepared figures. GY Z, ZC C, XF S and HF L collected data and performed the statistical analysis. All authors have read and approved the final manuscript.

Funding

None.

Data availability

All data generated or analyzed during this study are included in this published article.

Declarations

Ethics and consent to participate

The study was approved by ethics committee of Wuxi Ninth People’ s. Hospital Affiliated to Suzhou University (No: KT202017026) and Yancheng First Hospital Affiliated to Nanjing University Medicine School (No. YC2017101). Written informed consent for participation was obtained from the patient.

Consent for publication

Written informed consent to publish was obtained from all individuals.

Competing interests

The authors declare that they have no competing interest.