**1. Introduction**

#### **1.1 Anterior crucial ligament reconstruction and tibial tunnel placement**

The anterior cruciate ligament (ACL) is a critical knee joint, bone-to-bone connected, stability ligament that is attached from an anterior location of the proximal tibia to a posterior location of the distal femur. The ACL is highly susceptible to failure during athletic activities and slip-fall events. The goal of ACL reconstruction surgery is to rebuild the ligament attachments as closely as possible to the native anatomy in order to restore pre-injury knee function and normal proprioception in

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*Proprioception*

**References**

[1] Partanen J. Different types of fibrillation potentials in human needle EMG. In: Turker H editor. Electrodiagnosis in new frontiers of clinical research. Rijeka, Croatia: Intech 2013, http://dx.doi.org/10.5772/55352

muscle afferents to the cerebral cortex and its possible role in motor control. Physiological Reviews

[10] Schieppati M, Nardone A, Siliotto R, Grasso M. Early and late stretch responses of human foot muscles induced by perturbation of stance. Experimental Brain Resarch

[11] Grey MJ, Ladouceur M,

Andersen JB, Nielsen JB, Sinkjær T. Group II muscle afferents probably contribute to the medium latency soleus stretch reflex during walking in humans. The Journal of Physiology

[12] Knikou M. The H-reflex as a probe: Pathways and pitfalls. Journal of Neuroscience Methods 2008;17:1-12.

[13] Metso AJ, Palmu K, Partanen JV. Compound nerve conduction velocity -

[14] Nardone A, Schieppati M. Mediumlatency response to muscle stretch in human lower limb: estimation of conduction velocity of group II fibres and central delay. Neuroscience Letters

[15] Kakuda N, Miwa T, Nagaoka M. Coupling between single muscle spindle afferents and EMG in human wrist extensor muscles: physiological evidence of skeletofusimotor (beta) innervation. Electroencephalography

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[2] Preston and Shapiro, editors. Electromyography and neuromuscular disorders: Clinical-electrophysiologic correlations. 2013. London: Elsevier.

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Tataroglu C, Aydogdu I, Karapinars N. Adductor T and H reflexes in humans. Muscle & Nerve 2006;34:640-645.

[7] Burke D, Gandevia SC, McKeon B. The afferent volleys responsible for spinal proprioceptive reflexes in man. The Journal of Physiology

[8] Yusal H, Larsson L-E, Efendi H, Burke D, Ertekin C. Medium-latency reflex response of soleus elicited by peroneal nerve stimulation. Experimental Brain Research

[9] Wiesendanger M, Miles TS. Ascending pathway of low-threshold

Neuromuscular & Electrodiagnostic Medicine. Don't perform dermatomal somatosensory evoked potentials (SEPs) for a pinched nerve in the neck or back, as they are an unproven diagnostic procedure. 2015, February 10.

[4] Burke D. Clinical uses of H reflexes of upper and lower limb muscles. Clinical Neurophysiology Practice.

[5] Partanen J. F-vaste ja H-refleksi. Chapter 5.1. In: Lang H, Partanen J, Häkkinen V, Larsen A. editors. Sähköiset hermomme. Turku: The Society of Clinical Neurophysiology in Finland

the affected knee [1]. Personalized medicine in surgery allows the customization of insertion sites, graft size, tunnel placement, and graft tension for each individual patient [2]. A critical pre-operative decision concerns the placement of a tibial-femoral tunnel mimicking the native orientation of the ACL attachment [2]. Surgeons need to consider particular aspects of the local anatomy and, by extension, the biomechanical artifacts introduced during surgery. Here, we report an alternative approach based on the understanding of knee affordances to guide surgeons in the design of knee reconstruction strategies.

As aforementioned, an important predictor of clinical outcome during ACL reconstruction is tunnel placement [3, 4]. Roof impingement occurs when an ACL graft prematurely contacts the intercondylar roof before the knee reaches terminal extension. A tibial tunnel anterior to the tibial intersection of the intercondylar roof's slope allows the distal half of the roof to impinge on the anterior surface of the graft (*arrow I* in **Figure 1(a)**). Impingement syndrome occurs when the relationship between two articular components are incongruous, with resulting friction, inflammation, and degeneration [6]. Failure of grafts placed anteriorly is likely due to the impact of the bony roof on the graft's anterior surface during knee extension (**Figure 1(b)**) [5].

#### **Figure 1.**

*(a) Schematic representation for the surgical placement of the tibial-femoral tunnel, presenting the possibility for uniform motion transmission within the knee.* The (positive) affordance based *approach encourages surgical designers to customize the position of the tibial-femoral tunnel to intersect with the instantaneous knee screw (IKS or \$). The point of contact (c) is determined from femoral and tibial velocity vectors during joint movement (VF and VT, respectively). (b) Radiographic and magnetic resonance images (MRI) of an exemplar of tibia tunnel placement leading to roof impingement during ACL reconstruction.* Negative affordances *(severe and moderate impingement) inform about the tunnel locations to avoid, in order to prevent roof impingement of the ACL. Severe roof impingement occurs when the surgeon places the tibial tunnel in a local totally anterior to the slope of the intercondylar roof (top). Moderate roof impingement occurs when the surgeon places the tibial tunnel in a local partially anterior to the slope of the intercondylar roof (middle). A graft may also become impinged when the surgeon places the tibial tunnel in a local entirely posterior and parallel to the slope of the intercondylar roof (bottom). An impinged graft has a low, uniform signal intensity on the MRIs. The original schematic and images were published previously [5] and are used by the permission of Dr. Stephen Howell.*

**53**

with one another.

*The Knee Proprioception as Patient-Dependent Outcome Measures within Surgical…*

To our knowledge, this is the first study to use psychological theory to address this surgical design concept [7]. Traditional rating systems to assess clinical outcome after joint arthroplasty are often based on the surgeon's objective ratings, such as range of motion and strength, or clinical ratings of function and pain. However, the patient's perceptions after arthroplasty may differ significantly from those of their clinician. Moreover, surgeons often underappreciate the needs and views of their patients [8]. There is, therefore, increasing awareness of the need to include patient-reported outcome (PRO) instruments in the evaluation of surgical procedures. Indeed, these patient-centered assessments of treatment outcomes are becoming today's standard [9]. Patient-reported outcome metrics (PROMs) can be simply described as a patient's health status self-report. A 'forgotten joint score', corresponding to when a patient forgets the artifact in their everyday life, was introduced in PROM as the ultimate goal in joint reconstruction [10]. 'Forgotten joint scores' are often observed in patients after surgery [11]. Nevertheless, these ratings do not replace the need to understand the general role of artifacts and affordances in reconstruction surgery. This study aims to identify measurable invariants using a (positive) affordance-based design strategy for structural tunnel placement during

Current approaches in design science are characterized by a strong emphasis on methods as opposed to theory. Herbert Simon [12] was one of the early proponents studying design as a science. In the 1960s, Simon criticized the lack of a theoretical basis in design methods, describing such ad hoc methods as 'cook-book approaches.' Novel conceptual frameworks for design allow engineers to better describe and solve problems at the system level, such as those involving user interactions. We propose a conceptual approach for design based on affordances, a concept used in

'Architecture and design do not have a satisfactory theoretical basis,' wrote psychologist James J. Gibson three decades ago. He also asked, 'can an ecological approach to the psychology of perception and behavior provide it?' [13]. Gibson's affordances theory describes how animals perceive their environment [14]. We applied Gibson's concept of affordance to the design of artifacts, in particular

A decade after Gibson's seminal work, another psychologist, Donald A. Norman,

Ecological psychologist William Warren has applied the concept of affordances to the design of specific artifact-user relationships, such as the height of stairway steps [18]. His approach relied on the ratio of leg height to step height. Paola Cesari followed up on Warren's stair climbing studies by showing that older people

use Gibson's theory of affordance to understand artifact design [15]. However, Norman's approach stopped short of incorporating the concept of affordance as fundamental to the design of any artifact [16]. When Norman revised the 1988 edition of his book in 2013, he rejected the ecological theory. He noted that the term affordance was often misused by psychologists, and as a result, he introduced the term 'signifier.' Signifiers make explicit that affordances are inputs used during cognitive deliberation for creating internal mental representations, which contradicts Gibson's claims that, if a designer successfully makes affordances possible, the artifact directly informs how it can be used—which is the hallmark of successful design. Intriguingly, in a recent study [17], Norman regrets that different psychology fields and design science have become separate silos unable to communicate

*DOI: http://dx.doi.org/10.5772/intechopen.94887*

ACL reconstruction.

**2. Affordance-based design**

the study of perception in ecological psychology.

anatomic artifacts, which impacts on their biomechanics.

*The Knee Proprioception as Patient-Dependent Outcome Measures within Surgical… DOI: http://dx.doi.org/10.5772/intechopen.94887*

To our knowledge, this is the first study to use psychological theory to address this surgical design concept [7]. Traditional rating systems to assess clinical outcome after joint arthroplasty are often based on the surgeon's objective ratings, such as range of motion and strength, or clinical ratings of function and pain. However, the patient's perceptions after arthroplasty may differ significantly from those of their clinician. Moreover, surgeons often underappreciate the needs and views of their patients [8]. There is, therefore, increasing awareness of the need to include patient-reported outcome (PRO) instruments in the evaluation of surgical procedures. Indeed, these patient-centered assessments of treatment outcomes are becoming today's standard [9]. Patient-reported outcome metrics (PROMs) can be simply described as a patient's health status self-report. A 'forgotten joint score', corresponding to when a patient forgets the artifact in their everyday life, was introduced in PROM as the ultimate goal in joint reconstruction [10]. 'Forgotten joint scores' are often observed in patients after surgery [11]. Nevertheless, these ratings do not replace the need to understand the general role of artifacts and affordances in reconstruction surgery. This study aims to identify measurable invariants using a (positive) affordance-based design strategy for structural tunnel placement during ACL reconstruction.

## **2. Affordance-based design**

*Proprioception*

design of knee reconstruction strategies.

extension (**Figure 1(b)**) [5].

the affected knee [1]. Personalized medicine in surgery allows the customization of insertion sites, graft size, tunnel placement, and graft tension for each individual patient [2]. A critical pre-operative decision concerns the placement of a tibial-femoral tunnel mimicking the native orientation of the ACL attachment [2]. Surgeons need to consider particular aspects of the local anatomy and, by extension, the biomechanical artifacts introduced during surgery. Here, we report an alternative approach based on the understanding of knee affordances to guide surgeons in the

As aforementioned, an important predictor of clinical outcome during ACL reconstruction is tunnel placement [3, 4]. Roof impingement occurs when an ACL graft prematurely contacts the intercondylar roof before the knee reaches terminal extension. A tibial tunnel anterior to the tibial intersection of the intercondylar roof's slope allows the distal half of the roof to impinge on the anterior surface of the graft (*arrow I* in **Figure 1(a)**). Impingement syndrome occurs when the relationship between two articular components are incongruous, with resulting friction, inflammation, and degeneration [6]. Failure of grafts placed anteriorly is likely due to the impact of the bony roof on the graft's anterior surface during knee

*(a) Schematic representation for the surgical placement of the tibial-femoral tunnel, presenting the possibility for uniform motion transmission within the knee.* The (positive) affordance based *approach encourages surgical designers to customize the position of the tibial-femoral tunnel to intersect with the instantaneous knee screw (IKS or \$). The point of contact (c) is determined from femoral and tibial velocity vectors during joint movement (VF and VT, respectively). (b) Radiographic and magnetic resonance images (MRI) of an exemplar of tibia tunnel placement leading to roof impingement during ACL reconstruction.* Negative affordances *(severe and moderate impingement) inform about the tunnel locations to avoid, in order to prevent roof impingement of the ACL. Severe roof impingement occurs when the surgeon places the tibial tunnel in a local totally anterior to the slope of the intercondylar roof (top). Moderate roof impingement occurs when the surgeon places the tibial tunnel in a local partially anterior to the slope of the intercondylar roof (middle). A graft may also become impinged when the surgeon places the tibial tunnel in a local entirely posterior and parallel to the slope of the intercondylar roof (bottom). An impinged graft has a low, uniform signal intensity on the MRIs. The original schematic and images were published previously [5] and are used by the permission* 

**52**

*of Dr. Stephen Howell.*

**Figure 1.**

Current approaches in design science are characterized by a strong emphasis on methods as opposed to theory. Herbert Simon [12] was one of the early proponents studying design as a science. In the 1960s, Simon criticized the lack of a theoretical basis in design methods, describing such ad hoc methods as 'cook-book approaches.' Novel conceptual frameworks for design allow engineers to better describe and solve problems at the system level, such as those involving user interactions. We propose a conceptual approach for design based on affordances, a concept used in the study of perception in ecological psychology.

'Architecture and design do not have a satisfactory theoretical basis,' wrote psychologist James J. Gibson three decades ago. He also asked, 'can an ecological approach to the psychology of perception and behavior provide it?' [13]. Gibson's affordances theory describes how animals perceive their environment [14]. We applied Gibson's concept of affordance to the design of artifacts, in particular anatomic artifacts, which impacts on their biomechanics.

A decade after Gibson's seminal work, another psychologist, Donald A. Norman, use Gibson's theory of affordance to understand artifact design [15]. However, Norman's approach stopped short of incorporating the concept of affordance as fundamental to the design of any artifact [16]. When Norman revised the 1988 edition of his book in 2013, he rejected the ecological theory. He noted that the term affordance was often misused by psychologists, and as a result, he introduced the term 'signifier.' Signifiers make explicit that affordances are inputs used during cognitive deliberation for creating internal mental representations, which contradicts Gibson's claims that, if a designer successfully makes affordances possible, the artifact directly informs how it can be used—which is the hallmark of successful design. Intriguingly, in a recent study [17], Norman regrets that different psychology fields and design science have become separate silos unable to communicate with one another.

Ecological psychologist William Warren has applied the concept of affordances to the design of specific artifact-user relationships, such as the height of stairway steps [18]. His approach relied on the ratio of leg height to step height. Paola Cesari followed up on Warren's stair climbing studies by showing that older people perceive stairs differently than young people. However, the ratio between step height and the distance between the stepping foot and the top edge of the step was similar in both groups [19].

Since the concept of 'affordance' was introduced almost 40 years ago, it has been used in a variety of fields, including child psychology [20], the design of graphical user interfaces [21], mobile robots [22], control room interfaces [23], and more recently, in engineering design [24–26]. The impetus for any design project can be understood in terms of creating and changing affordances. The design process is the construction of an artifact that offers specific affordances, but not certain undesired affordances. An artifact with more positive affordances is considered better, while an artifact with more negative affordances is considered worse. However, this approach does not follow ecological psychology, but instead, it addresses the difficulty of identifying affordances with engineering [27].

Maier and Fadel coined the term artifact-artifact affordance (AAA) [24, 25]; however, AAA has not been properly incorporated within the larger theory of affordances. Although AAA was developed as a new concept, the idea that inanimate objects offer action possibilities in an organism is a foundational concept known since Gibson's work in ecological psychology. The ecological approach demonstrates how animal (including human) perception and action is continuous with interactions between inanimate physical systems, or the world in general. The entrainment of separate limbs during biological coordination, for example, follows the same physical laws as entrainment between two pendulum clocks or other purely mechanical (inanimate) systems [28]. The fact that interactions between inanimate and animate systems are continuous precludes the need to identify AAA as a distinct category.

In short, these concepts should be used with great care if knowledge is to be gathered. In the present study, we used a surgical technique as an example of how the theory of affordances may be utilized for affordance-based design.
