Skeletal Manifestations of Gender-Affirming Medical Interventions for Aiding in the Preliminary Identification of Trans Individuals

Abstract

Because of systemic discrimination, transgender individuals are at greater risk of being the victims of violence and of homicide. Accurate post-mortem identification from skeletonized remains of transgender individuals must be incorporated into a new standard for forensic anthropological analyses. A critical component of any investigation is the assessment of skeletal remains for evidence of gender-affirming care. A systematic review of the current medical literature was conducted to compile in one document descriptions of changes that could be used by forensic anthropologists to recognize skeletal manifestations resulting from gender-affirming surgeries, including facial feminization surgery (FFS), shoulder width reduction surgery, and limb-lengthening procedures. These skeletal changes, when present bilaterally and without evidence of healed trauma, serve as key indicators of a person’s transgender identity postmortem. Recognizing common patterns in bone structure alterations due to gender-affirming interventions will assist in identifying transgender individuals and providing closure for families. By integrating markers from gender-affirming care practices into forensic investigations, this research contributes to more inclusive and rigorous forensic investigations.

1. Introduction

Transgender individuals are statistically more likely to be the target of violent crimes than their cisgender counterparts [1]. For example, in Canada, the Survey of Safety in Public and Private Spaces estimates that one million Canadians are “sexual minorities” and states that they are more likely to have experienced physical or sexual assault than heterosexual Canadians [1]. Transgender individuals are also more likely to have poor mental health compared to their cisgender peers and are more likely to have seriously contemplated suicide (40% of transgender individuals versus 15% of cisgender individuals) [2].

Although forensic anthropologists focus on estimating biological sex, it is necessary to consider both sex and gender for ethical, methodological, and theoretical reasons when developing, testing, and applying forensic methods, since some people may be targeted because of their gender, which may not correspond to a given biological sex [3]. Sex and gender are terms that tend to be used interchangeably but are distinct concepts constructed using different sets of criteria (See [4] for an overview of key terms and concepts with a reference to osteology). Gender is a fluid social construct that varies through time and space based on economic, political, and historical contexts. Multiple cultures from across the globe have a non-binary gender system, such as Two-Spirit individuals in many Indigenous North American cultures [5], and Calalai, Calabai, and Bissu in Indonesia’s Bugi population [6,7]. Even the government of the United States has started issuing passports that allow for an option that is not male or female. Passport applicants have the option of “…another gender identity (X) as the gender…” [8].

Sex is a biological construct defined using various anatomical, physiological, hormonal, phenotypic, and genetic criteria [4]. An individual’s gender does not necessarily coincide with one’s biological sex. Neither sex or gender are binary, and both may change over the course of one’s life or when different criteria are applied to define categories. A person may be categorized as “female” using external genitalia but “male” using hormone levels, which is what happened to the South African athlete Caster Semenya when she wanted to compete internationally as a female but had “male levels” of testosterone (see [9] for a detailed critique). Using other biological criteria, there are at least five biological sexes that can be consistently identified at measurable frequencies using chromosomal criteria in human populations, including XO, XX, XY, XXY, and XYY.

In a forensic context, the estimated sex of an individual may vary when different methods are used, even when the same skeletal elements are assessed [10]. In a previous publication [10], one of us (JA) demonstrated how different methods involving the pelvis and the femur would result in different estimates in a case study involving a very small individual whose sex was documented as male. In this case, the joint measurements of the femur were at or below the female mean, and this individual had a clear ventral arc. Using these joint measurements and the morphoscopic assessment of the ventral arc, the individual’s sex could be estimated as female. With these methods, a probabilistic statement is not possible. In contrast, sex was estimated as male with over 80% likelihood when logistic regression was used with five measurements, including both femur joints, innominate height, iliac breadth, and an alternative measurement of the os pubis. Using the same skeletal elements from the same person, there were two very different estimates of sex using what can be described as reliable methods that considered highly sexually dimorphic skeletal elements. Given the complexity of sex and gender, an alternative protocol for identifying trans people is required, one that is not dependent on a binary approach to estimate biological sex but rather focuses on assessing evidence of gender-affirming care.

Gender-affirming care refers to any combination of procedures or treatments designed to affirm an individual’s gender identity [11,12]. About three quarters of transgender individuals have indicated that they need to transition medically in some form [13]. This statistic paired with the increased likelihood of being a victim of a targeted attack or suicide means that there is a disproportionate need for identifying the remains of transgender individuals [1,2]. Since gender-affirming care is a gender-based modification, estimating sex based on biological criteria may not be effective in creating a profile for the preliminary identification of a transgender individual. An analysis of markers on bones left by gender-affirming care practices in conjunction with more traditional approaches to estimation methods is a more robust approach for identifying the remains of an individual as transgender. In this paper, we present the results of a systematic review of the medical literature describing gender-affirming care options, with a focus on the skeletal changes resulting from specific interventions. We compiled and present this information in the manner that is most useful to forensic anthropologists tasked with collecting information for a preliminary identification from skeletal remains. The primary goals of this research are to integrate the knowledge and effects of common gender-affirming medical interventions for a more robust forensic anthropological analysis, to bring closure to the families of the deceased, and to advocate for fundamental human rights to identification for transgender individuals.

2. Methods

A comprehensive review of articles available on PubMed was completed (between 15 September 2023 and 15 March 2024), using different combinations of keywords, including pelvis, bone, skull, facial feminization surgery, medical interventions for transgender patients, transgender, height, hormone replacement therapy, and gender-affirming surgery. PubMed was selected because it is the largest database of biomedical literature, with over 36 million citations from MEDLINE, life science journals, and online books. The information has been compiled in a way that would be most useful to forensic anthropologists, focusing on gross recognizable changes to the skeleton, and has been presented in a way that aligns with a standard anatomical approach, beginning superiorly with the skull and continuing inferiorly.

3. Results

3.1. Skull

Facial feminization surgery (FFS) is an umbrella term used to explain several plastic surgery procedures used to feminize the skull, specifically targeting features that are traditionally considered more masculine, including the mental protuberance and gonial angle, supraciliary arch, and nasal bone [14]. It is important to note that alone, a single surgery such as a rhinoplasty does not indicate that an individual is transgender. Evidence of multiple feminizing surgeries performed bilaterally is required to suggest that an individual was transgender. One of the more common approaches is an osteotomy, which is a surgical technique performed to reshape a bone through the cutting and removal of part of the surrounding or impacted bone [15].

3.1.1. Superciliary Arch

The procedure used to reduce the prominence of the supraciliary arch varies with the anatomy of the frontal sinus. A frontal bone with a small frontal sinus may only need superficial bone contouring to achieve the feminization of the superciliary arch, which is done by burring or shaving the bone to obtain the appropriate contour [16], whereas a pronounced frontal sinus would require an osteotomy and setback with fixation (Figure 1a), more commonly called a “frontal sinus setback” [16,17]. A frontal sinus setback can be identified by the presence of small titanium plates and screws fixing the frontal bone back onto the rest of the skull (Figure 1b). The plates and screws will also be found bilaterally, which can indicate a planned cosmetic surgery rather than reconstructive surgeries following injuries, which are more random and less symmetrical.

3.1.2. Nasal Bone

Rhinoplasties are used to increase the nasofrontal and nasolabial angles. With the softening of the angles, the nose appears more feminine. This is completed bilaterally to ensure that the nose is symmetrical [16,18,19] (Figure 1b). Rhinoplasty is a common cosmetic procedure and alone is not indicative of someone who is transgender.

3.1.3. Mental Protuberance and Gonial Angle

A sliding genioplasty is used to reshape the appearance of the mental process (see also [20] for other possible indirect impacts on the mandible). This process involves cutting the mental protuberance from the mandible, moving the chin, and then fixing the mental protuberance back onto the mandible (Figure 1). Titanium plates, mesh, or screws would be found bilaterally. The contouring of the jaw to soften the gonial angle is also performed bilaterally [18] (Figure 1b).

3.2. Clavicle

Shoulder width reduction surgery, or shoulder feminization surgery, is an option for individuals seeking feminizing surgery. The procedure involves the shortening of the clavicle but has not been described in detail in the medical literature. The procedure stems from open reduction and internal fixation surgery, a surgery used to treat complex middle third clavicle fractures [21]. This procedure involves the removal of a segment of the middle third of the clavicle, with plates used to fix the bone [21,22]. Shoulder feminization surgery uses the foundation of this procedure for its aesthetic results. The shortening of both clavicles with the presence of plates bilaterally with no evidence of healed trauma to the clavicle would indicate that the individual underwent feminizing surgeries (Figure 2).

3.3. Pelvis

Various hormone therapies are available to trans people. The administration of gonadotropin releasing hormone antagonists (GnRHa), or puberty blockers, as well as gender-affirming hormones, such as estrogen and testosterone, along with their timing relative to development, will have a varying impact on pelvis morphology and a varying systemic impact on bone density throughout the skeleton [23]. However, these changes to the skeleton have not currently been described or assessed in the medical literature in a way that is helpful to forensic anthropologists in the identification of a transgender individual.

3.4. Femur, Tibia, and Fibula

Limb-lengthening surgery to increase height involves the lengthening of the shaft of leg bones [24]. This procedure can involve the tibia and fibula, or the femur [24]. The most common cosmetic procedure is bilateral tibial lengthening, in which an osteotomy of both the tibia and fibula is performed. Indicators of limb-lengthening surgery can include an internal rod used to fix the bone or evidence of new bone growth in the midshaft of the bone that was the target of the procedure. Note how the osteotomy is performed at the midshaft of the tibia and on the distal third of the fibula (Figure 3). The process for femoral lengthening is similar in location to the tibia, with the osteotomy performed at midshaft. Typically, either the femur or the tibia and fibula are affected (Figure 3). As with other procedures, limb-lengthening surgery alone is not necessarily confirmation that the individual was trans.

4. Discussion and Conclusions

Many of the surgical procedures applied to gender-affirming care are derived from other applications, as evidenced by shoulder width reduction surgery and limb-lengthening surgery, and because not everything will appear in one’s “osteobiography” there may not always be skeletal evidence that the deceased is transgender. Forensic anthropologists would already be assessing the remains of an unknown individual for evidence of healed premortem trauma, surgeries, screws/plates, etc., which may aid with identification. The same information that is already being collected may also help with identifying trans individuals. Any one change that is visible in bone may not necessarily indicate that an individual was transgender. Forensic anthropologists should look for a pattern in the changes to an individual’s bone structure. First, gender-affirming care interventions include bilateral symmetry of surgeries on bones. Second, the bones with noticeable changes should be devoid of evidence of healed trauma. Third, the procedures should not occur in isolation, but in the presence of other feminizing or masculinizing surgeries. Surgeries for aesthetic purposes, including gender-affirming care procedures, will be much less random than those for traumas, due to the need for a specific desired effect. For example, the same procedure used for complex middle third clavicle fractures is used in shoulder width reduction surgery. If the procedure was used to treat an injury to the bone, there would be evidence of healed trauma and it would be restricted to one clavicle. For trans individuals, the same procedure for shoulder width reduction would be performed bilaterally in the same location on each clavicle, with a sharper line where the osteotomy was performed.

In addition to the evidence of surgery, estimating sex may assist with the identification of a trans individual. In some cases, a pronounced discrepancy between the pelvic dimensions and/or morphology, and the presence of feminizing or masculinizing surgeries may be evident. For example, an individual whose sex is estimated as male using a probabilistic approach with a high likelihood of 95 to 99% using the pelvis and other skeletal elements (for example, [10]), and who has skeletal evidence consistent with feminization surgeries, may suggest that the individual was transgender. In this one possible scenario, their biological sex assigned at birth was male, but they had likely transitioned and/or had initiated hormone therapies after puberty and may have identified as a woman before death. This example also illustrates the importance of considering both sex and gender in a forensic investigation. It is worth noting that in a few rare cases, someone’s sex may be estimated as male with a high probability, even though their sex was assigned as female at birth and they identified as a woman. One of us (JA) has presented details elsewhere on why some methods fail to estimate the documented sex using various infracranial skeletal elements [10,25].

Several gaps in the literature were identified while completing this research. In some cases, the data are not available. For example, the general impacts of hormones and their varying impacts related to the timing of interventions relative to puberty on skeletal morphology in transgender youth are not well documented in the medical literature. Although the general impacts of “sex hormones,” such as estrogen and testosterone, are generally understood, there is no published research on how gender-affirming hormones impact the morphology of the pelvis, specifically when used in conjunction with gonadotropin-releasing hormone antagonists or puberty blockers [12]. Puberty blockers are typically started around the age of 12, and gender-affirming hormones are typically added to the treatment regimen around the age of 16 [12]. With other data, only brief summaries of gender-affirming procedures can be found on hospital websites and surgeons’ individual business websites, but detailed information about specific surgical procedures is considered proprietary and has not been described in the medical literature.

The updating of standards for reporting of sex and gender is essential in forensic anthropology (see [26,27,28]). These new reporting standards must be accompanied with new methods for the identification of deceased individuals using skeletal data for complementary reasons that involve the integration of ethical, methodological and theoretical considerations [29,30]. First, trans rights are human rights, and a strong ethical case can be made to be more inclusive in the development of new forensic methods. As some of us have been stating for over 15 years publicly [31] and in scholarly forensic publications [32], a more inclusive approach to research and practice in forensic anthropology that considers the biocultural factors that affect variation and that also preserves the humanity of the deceased will assist in protecting the living [33,34]. Second, given the complexity of human variation, a more inclusive approach in forensic investigations is also methodologically and theoretically more robust. For example, Albanese [10] developed a metric approach for sex estimation that is not population-specific by rejecting a typological approach to understanding human variation that racialized already marginalized people; Albanese and colleagues [35] developed an alternative approach to stature estimation by demonstrating how group specificity based on typological concepts of human variation is highly problematic; Albanese and colleagues [30] systematically demonstrated that regardless of what terms are used (population affinity, ancestry, or race), widely available methods provide very poor results that will undermine identification while further marginalizing the living. With few exceptions (for example [29,36,37,38], which were influenced by [10,32,35,39]), few forensic anthropologists have pursued this more robust approach that integrates ethical, methodological and theoretical issues to develop new forensic methods. Despite the clear gaps in the information currently available, the impacts of gender-affirming procedures can be detected on the skeleton, and this assessment must be included as an essential part of any thorough investigation conducted by forensic anthropologists. The routine integration of an assessment of gender-affirming procedures on the skeleton is a critical step in preliminary identification in forensic anthropology.