Total hip arthroplasty preoperative planning for childhood hip disorders’ sequelae: Focus on developmental dysplasia of the hip

Abstract

Developmental dysplasia of the hip (DDH) poses significant challenges in both childhood and adulthood, affecting up to 10 per 1000 live births in the United Kingdom and United States. While newborn screening aims to detect DDH early, missed diagnoses can lead to severe complications such as hip dysplasia and early onset osteoarthritis in adults. Treatment options range from less invasive procedures like hip-preserving surgery to more extensive interventions such as total hip arthroplasty (THA), depending on the severity of the condition. Preoperative planning plays a critical role in optimizing surgical outcomes for DDH patients undergoing THA. This includes accurate imaging modalities, precise measurement of acetabular bone stock, assessment of femoral head subluxation, and predicting prosthesis size and leg length discrepancy. Recent advancements artificial intelligence and machine learning offer promising tools to enhance preoperative planning accuracy. However, challenges remain in validating these technologies and integrating them into clinical practice. This editorial highlights the importance of ongoing research to refine preoperative strategies and improve outcomes in DDH management through evidence-based approaches and technological innovations.

Key Words: Developmental dysplasia of the hip; Childhood hip disorders; Total hip arthroplasty; Total hip replacement; Preoperative planning

Core Tip: Developmental dysplasia of the hip (DDH) presents challenges from infancy to adulthood. Early detection is critical, as untreated DDH can lead to severe hip dysplasia and osteoarthritis. Treatment ranges from conservative approaches to total hip arthroplasty (THA). Preoperative planning for THA in DDH involves precise imaging, acetabular assessment, and prediction of prosthesis size. Advances in artificial intelligence hold promise for enhancing accuracy in surgical planning. However, validating these technologies and integrating them into clinical practice are ongoing tasks. This editorial emphasizes continual research to refine preoperative strategies and leverage technological advancements for improved DDH management outcomes.

INTRODUCTION

Developmental dysplasia of the hip (DDH) affects up to 10 per 1000 live births in the United Kingdom and United States[1,2]. Despite newborn screening, DDH can occasionally go undetected. If left untreated, it is one of the most common causes of hip dysplasia in adults[3] and the leading cause of early onset hip osteoarthritis[4]. DDH is known to have a genetic predisposition, with genes such as COLIAI and GDF5 being directly association with DDH[5-7], with those of native American and causation population being at the highest risk[8].

Sequelae of DDH are among the most common childhood disorders requiring total hip arthroplasty (THA) in adulthood[3-7]. Other conditions included among childhood disorders that could require adult surgical management are: Perthes Disease, Slipped Capital Femoral Epiphysis, childhood septic arthritis, multiple surgical procedures[1-4].

Hip dysplasia in adults has differing presentations, varying from minor hip instability to subluxation and dislocation of the hip[9]. Severe complications such as osteonecrosis can occur if interventions do not work[10]. While less invasive surgeries, such as hip preserving surgery, should be performed as a first line, osteotomies and THA may be necessary as a last resort[11]. Ensuring that DDH is treated in childhood is crucial to prevent these complications.

THA is one of the most commonly performed orthopaedic procedures[12], with DDH providing a large caseload for orthopaedic surgeons[13]. The THA has a long, and research driven, history dating back to 1891[14]. In the United States alone, over 260000 THA are performed every year[15]. With demands increasing, projections suggest that by 2040 there will be over 700000 THA performed per annum[15].

Oommen[16] explored the need for THA in adults with childhood hip disorders. In DDH, femoral neck retroversion progresses to excessive anteversion, narrowing the medullary canal[17]. Addressing the diaphysis-metaphysis mismatch is crucial, making meticulous preoperative planning essential for successful surgery. While classification systems, such as the Crowe Classification, subdivide DDH into grades[18], which can be used to determine the method of treatment and intervention for DDH, more can be done to improve the quality of, and evidence base behind, THA in this context[16-18].

This editorial emphasizes the need for detailed and appropriate preoperative planning for THA, building on the work of Oommen AT[16], aiming to focus on preoperative planning of a THA for the treatment DDH’s sequelae.

PREOPERATIVE PLANNING

THA for sequelae of childhood disorders could be challenging. Many factors play a relevant role in making these surgical treatments very complex and risky procedures. Among these, certainly the distortion of the normal anatomy of the hip and surrounding tissues is a key aspect[9-11,16].

For these reasons, bony and soft tissue anatomical changes must be assessed, especially for hips with prior surgical procedures. Furthermore, planning, templating, intraoperative soft tissue releases, identification of true acetabulum, and hip centre restoration should be fully studied and taken into consideration when planning to surgically treat this cohort of patients[11,16].

A valid preoperative THA planning starts from a full clinical hip examination with detailed neuromuscular assessment. In fact, these patients could have undertaken several prior surgeries with consequent bony and soft tissue modifications/alterations. A full clinical examination should be followed by an appropriate radiological examination. The following step is represented by preoperative templating. This practice provides essential information regarding the possible component sizes for the acetabulum and the femur. However, the information provided by the pre-operatory templating must be compared with the intraoperative findings, which, in the end, guide the decisions of the surgeons. Only navigation or robotic technology could allow a more proper use of the intraoperative planning, but these technologies are rarely available[16].

Preoperative planning can be broken down into the following stages[19-21]: Imaging modality; confirmation of acetabular position; estimate of acetabular bone stock; confirmation of femur head subluxation height; measurement of the combined anteversion; and Crowe classification; prediction of prosthesis size; leg length discrepancy (LLD); cup type; stem type.

Imaging modality

While conventional lateral and anterior-posterior radiographs are important in DDH classification[22,23], computed tomography (CT) and magnetic resonance imaging (MRI) scans can be used to add more precise three-dimensional imaging to provide further insight into the extent of the DDH. However, most of the majority of the preoperative radiographic factors have been validated on conventional radiographs[24,25]. As such, further studies could be used to validate CT and MRI modalities[26], or could utilise artificial intelligence (AI) and machine learning (ML) to use imaging parameters to enhance their predictive capacity by utilizing imaging parameters.

Confirmation of acetabular position and acetabular bone stock estimation

The choice of imaging modality for accurately estimating acetabular bone stock remains contentious, with conflicting evidence supporting both two-dimensional radiographic images and three-dimensional imaging[27,28]. Further work could evaluate the current literature, arriving at a quantitative determination regarding the optimal method for measuring acetabular bone stock.

Measurement of femur head subluxation height, and combined anteversion

Research has demonstrated that Crowe grades II-IV deformities show significant shortening and increased anteversion compared to Crowe grade I hips[29]. Although, as per the previous sections, AI could be used to streamline this process. For this to be developed, a large retrospective cohort would be required, encouraging collaboration between institutions.

Crowe classification

While high levels of inter and intraobserver reliability has been reported for Crowe’s classification[30] validity has not been formally evaluated. While Crowe’s rating holds prognostic significance[31], its reliance on a two-dimensional anatomical model[30,32], inherently limits accuracy. Hartofilakidis et al[33] have developed an alternative classification, integrating functional measures alongside radiographic parameters. Future studies could compare these classifications to ascertain their respective clinical utility.

Prediction of prosthesis size

In a retrospective study, Ding et al[34] employed AI to integrate three-dimensional imaging for predicting the size and positioning of prostheses in THA. Their AI-driven model outperformed traditional two-dimensional manual templates, showing significantly greater consistency in determining femoral stem and cup sizes. This highlights AI's potential to improve accuracy in prosthesis size prediction. However, widespread implementation of this technology is currently limited, underscoring the necessity for larger studies to validate its effectiveness.

Leg length discrepancy

A common complication post THA for patients with severe dysplasia is an LLD, leading to gait abnormality[20,35]. Predicting LLD postoperatively is challenging, although a patient's Crowe classification often correlates with its occurrence. Guo et al[36] developed an equation to accurately estimate LLD. Given than LLD was stated as a large source of anxiety in DDH patients[35], this tool could improve patient experiences during surgery for DDH. Patients would have clearer expectations, enabling more accurate planning of subsequent physiotherapy and follow-up treatments.

Cup and stem type

The choice between cemented and uncemented cups in THA varies, and evidence suggests significant differences in outcomes. Cemented acetabular reconstruction has been associated with lower survival rates and higher revision rates[37]. As such, uncemented acetabular components are increasingly favoured due to better clinical outcomes. Evidence shows no significant differences between modular and monoblock stems[38,39].

The choice between cemented and uncemented cups in THA involves distinct surgical preparations. Cemented stems typically require shortening of the femoral metaphysis, and subtrochanteric shortening requires a cementless stem[40]. Therefore, selecting the appropriate cup type should consider both the general evidence base and the specific patient's condition. This highlights the importance of developing comprehensive guidelines and technical insights that accommodate these differences.

FUTURE WORKS

DDH is an area of orthopaedics that is in need of further research. At present, very few randomised controlled studies focus on the role of THA in DDH. Çatma et al[41] outline the superiority of a posterior approach to a THA to treat DDH, having better outcomes than an anterolateral approach; further highlighting another option to be considered in the preoperative planning stage.

With regards to pre-op rehabilitation, particularly of the abductor muscles, it has been shown that a good rehab program could improve hip range of motion, and functional outcomes for DDH patients after THA[42]; good results have been recorded with regards to physiotherapy programs before surgery[42-44]. However, given the available level of evidence for this practice[43,44], future studies should be performed to determine the extent to which this could help DDH patients. This could then be used to alter and improve guidelines, and could be used as a part of the preoperative plan for such patients.

CONCLUSION

THA for DDH sequelae is a challenging surgical procedure. Previous surgeries, anatomical bony and soft tissue variations and centre of rotation modifications pose a real threat to the surgeons dealing with this cohort of patients. Preoperative planning is particularly essential in this type of surgery, given its potentials to shed a light on very complex clinical scenarios. In conclusion, future research should place greater emphasis on preoperative planning to build a stronger evidence base for optimizing surgical approaches for Developmental DDH. The potential of AI, ML, and other advanced computational technologies should be explored further. It is also essential to evaluate the effectiveness of current preoperative planning methods in reducing operative complications through national audits and large-scale studies.