Morphology of the scaphotrapeziotrapezoid joint: A multi-domain statistical shape modeling approach.

The scaphotrapeziotrapezoid (STT) joint is involved in load transmission between the wrist and thumb. A quantitative description of baseline STT joint morphometrics is needed to capture the variation of normal anatomy as well as to guide staging of osteoarthritis. Statistical shape modeling (SSM) techniques quantify variations in three-dimensional shapes and relative positions. The objectives of this study are to describe the morphology of the STT joint using a multi-domain SSM. We asked: (1) What are the dominant modes of variation that impact bone and articulation morphology at the STT joint, and (2) what are the morphometrics of SSM-generated STT joints? Thirty adult participants were recruited to a computed tomography study of normal wrist imaging and biomechanics. Segmentations of the carpus were converted to three-dimensional triangular surface meshes. A multi-domain, particle-based entropy system SSM was used to quantify variation in carpal bone shape and position as well as articulation morphology. Articular surface areas and interosseous proximity distributions were calculated between mesh vertex pairs on adjacent bones within distance (2.0 mm) and surface-normal angular (35°) thresholds. In the SSM, the first five modes of variation captured 76.2% of shape variation and contributed to factors such as bone scale, articular geometries, and carpal tilt. Median interosseous proximities-a proxy for joint space-were 1.39 mm (scaphotrapezium), 1.42 mm (scaphotrapezoid), and 0.61 mm (trapeziotrapezoid). This study quantifies morphological and articular variations at the STT joint, presenting a range of normative anatomy. The range of estimated interosseous proximities may guide interpretation of imaging-derived STT joint space.

Magnetic Resonance Imaging Assessment of Ulnar Wrist Pain: A Practical Guide for Surgeons.

Ulnar-sided wrist pain is a challenging clinical scenario due to multiple overlapping pathologies and involved anatomic structures. Advanced imaging such as magnetic resonance imaging can be used as an effective diagnostic adjunct if interpreted correctly. In this article, clinically relevant structures and radiographic correlates of the ulnar wrist are discussed and a corresponding systematic approach to reviewing magnetic resonance imaging is presented.

Synthetic Tape Augmentation for Thumb Carpometacarpal Joint Instability: Surgical Technique.

Background Dorsal thumb carpometacarpal (CMC) instability can occur after traumatic injury and can lead to persistent pain and dysfunction of the hand. We present a case report of a joint-sparing technique for recurrent thumb CMC instability after failed Eaton-Littler procedure. Case Description We describe a technique to repair the dorsal radial ligament and augment the repair with dorsal synthetic tape. To illustrate this technique, we describe a patient who underwent the synthetic tape augmentation procedure for recurrent thumb CMC instability after a failed Eaton-Littler reconstruction. Preoperative and postoperative grip strength, appositional pinch, oppositional pinch, radial abduction, palmar abduction, and postoperative quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) were recorded. At final follow-up 18 months after surgery, the patient had returned to manual work without any functional sequelae. The thumb CMC joint was stable and his postoperative QuickDASH score was 15.9. Literature Review Thumb CMC instability has traditionally been treated with Eaton-Littler ligament reconstruction which uses a slip of flexor carpi radialis tendon to reconstruct the deficient ligaments. More recently, the importance of the dorsal radial ligament in joint stability has been recognized and new procedures have been described to reconstruct the dorsal radial ligament. To our knowledge, synthetic tape augmentation for thumb CMC instability has not yet been described for this pathology. Clinical Relevance Synthetic tape augmentation for dorsal thumb CMC instability may be considered in the management of dorsal thumb CMC joint instability.

Etiology and Diagnostic Challenges of Ulnar Wrist Pain in Pediatric and Adolescent Patients.

PURPOSE: Diagnosing the cause of ulnar-sided wrist pain can be difficult in the pediatric and adolescent age group. While frequently used, the diagnostic accuracy of magnetic resonance image (MRI), as compared with intraoperative arthroscopic findings, is not well-described in this population. This study aimed to determine concordance rates between magnetic resonance and arthroscopic findings depending on the specific ulnar wrist pathology. METHODS: A retrospective review was performed to identify pediatric and adolescent patients who underwent operative treatment of ulnar wrist pain between 2004 and 2021. Patients were included in the analysis if they were <18 years of age, complained of ulnar-sided wrist pain, underwent MRI of the affected wrist with an available report interpreted by a consultant radiologist, and had a diagnostic arthroscopy procedure within one year of imaging. Ulnar pathologies analyzed included triangular fibrocartilage (TFCC) tears, ulnotriquetral (UT) ligament tears, lunotriquetral ligament abnormalities, and ulnocarpal impaction. RESULTS: A total of 40 patients with a mean age of 15-years-old (range 11 to 17) were included in the analysis. Twenty-four were female, and approximately half had their dominant extremity affected. Most had a history of antecedent trauma (n = 34, 85%), but only 15/40 (38%) had a history of fracture. The mean duration of symptoms prior to presentation was six months (standard deviation, 7). The most common etiologies were Palmer 1B TFCC tears (n = 27, 68%) followed by UT split tears (n = 11, 28%). MRI overall demonstrated high specificity (82% to 94%), but low sensitivity (14% to 71%) for ulnar-sided wrist conditions. Accuracy varied between 70% and 83% depending on the specific injury. CONCLUSION: While MRI is a useful adjunct for determining the cause of ulnar wrist pathologies, findings are often discordant when compared with diagnostic arthroscopy. Surgeons should have a high degree of suspicion for TFCC-related pathology in the setting of positive provocative clinical examination despite negative MRI findings in young patients. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic IIb.

Inflammatory Markers Involved in the Pathogenesis of Dupuytren's Contracture.

Dupuytren's disease is a common fibroproliferative disease that can result in debilitating hand deformities. Partial correction and return of deformity are common with surgical or clinical treatments at present. While current treatments are limited to local procedures for relatively late effects of the disease, the pathophysiology of this connective tissue disorder is associated with both local and systemic processes (e.g., fibrosis, inflammation). Hence, a better understanding of the systemic circulation of Dupuytren related cytokines and growth factors may provide important insights into disease progression. In addition, systemic biomarker analysis could yield new concepts for treatments of Dupuytren that attenuate circulatory factors (e.g., anti-inflammatory agents, neutralizing antibodies). Progress in the development of any disease modifying biologic treatment for Dupuytren has been hampered by the lack of clinically useful biomarkers. The characterization of nonsurgical Dupuytren biomarkers will permit disease staging from diagnostic and prognostic perspectives, as well as allows evaluation of biologic responses to treatment. Identification of such markers may transcend their use in Dupuytren treatment, because fibrotic biological processes fundamental to Dupuytren are relevant to fibrosis in many other connective tissues and organs with collagen-based tissue compartments. There is a wide range of potential Dupuytren biomarker categories that could be informative, including disease determinants linked to genetics, collagen metabolism, as well as immunity and inflammation (e.g., cytokines, chemokines). This narrative review provides a broad overview of previous studies and emphasizes the importance of inflammatory mediators as candidate circulating biomarkers for monitoring Dupuytren's disease.

Detection of scapholunate interosseous ligament injury using dynamic computed tomography-derived arthrokinematics: A prospective clinical trial.

Scapholunate interosseous ligament injuries are a major cause of wrist instability and can be difficult to diagnose radiographically. To improve early diagnosis of scapholunate ligament injuries, we compared injury detection between bilateral routine clinical radiographs, static CT, and dynamic four-dimensional CT (4DCT) during wrist flexion-extension and radioulnar deviation. Participants with unilateral scapholunate ligament injuries were recruited to a prospective clinical trial investigating the diagnostic utility of 4DCT imaging for ligamentous wrist injury. Twenty-one participants underwent arthroscopic surgery to confirm scapholunate ligament injury. Arthrokinematics, defined as distributions of interosseous proximities across radioscaphoid and scapholunate articular surfaces at different positions within the motion cycle, were used as CT-derived biomarkers. Preoperative radiographs, static CT, and extrema of 4DCT were compared between uninjured and injured wrists using Wilcoxon signed rank or Kolmogorov-Smirnov tests. Median interosseous proximities at the scapholunate interval were significantly greater in the injured versus the uninjured wrists at static-neutral and maximum flexion, extension, radial deviation, and ulnar deviation. Mean cumulative distribution functions at the radioscaphoid joint were not significantly different between wrists but were significantly shifted at the scapholunate interval towards increased interosseous proximities in injured versus uninjured wrists in all positions. Median and cumulative distribution scapholunate proximities from static-neutral and 4DCT-derived extrema reflect injury status.

Wrist Motion Assessment in Tennis Players using Three-Dimensional Motion Capture and Dynamic Electromyography.

Background Tennis players often present with ulnar-sided wrist pain, which may reflect repetitive stress and/or faulty mechanics. There is a role for investigating the biomechanics of tennis strokes and how they may relate to wrist pathology. The purpose of this study was to investigate whether three-dimensional motion capture technology and dynamic electromyography (EMG), when used to study groundstrokes in elite junior tennis players, reveals patterns of upper extremity motion that may correlate with the development of clinically relevant pathology. Case Description Three-dimensional kinematic and EMG data were collected from two United States Tennis Association-ranked adolescent tennis players during groundstrokes. There were several observed differences in the two players' degree and timing of pronation/supination, ulnar/radial deviation, and flexion/extension during their strokes. Clinical Significance Advanced motion capture technology facilitates a nuanced understanding of complex movements involved in groundstroke production. This methodology may be useful for identifying athletes who are at risk for injury and guiding rehabilitation for players experiencing pain. Level of Evidence IV.

Dynamic Computed Tomography of the Distal Radioulnar Joint Versus Magnetic Resonance Imaging in Detecting Foveal Tears of the Triangular Fibrocartilage Complex.

BACKGROUND: Diagnosis of foveal triangular fibrocartilage complex (TFCC) tears remains difficult. The purpose of this study was to evaluate whether dynamic computed tomography (CT) of the distal radioulnar joint (DRUJ) has a higher sensitivity in detecting foveal tears of the TFCC when compared with magnetic resonance imaging (MRI). METHODS: A database query identified all patients above the age of 18 years with suspected foveal TFCC injuries who underwent bilateral dynamic CT imaging of the DRUJ, static 3T MRI, and subsequent wrist arthroscopy. All patients had evidence of foveal tenderness on clinical examination. The imaging results were validated with wrist arthroscopy. RESULTS: Twelve patients with a mean age of 31 years (range, 18-53 years) were identified. Eight patients were diagnosed with a complete foveal detachment of the TFCC on wrist arthroscopy. Of the 8 patients with a foveal tear on DRUJ arthroscopy, only 3 had a preoperative physical examination suggestive of DRUJ instability. Magnetic resonance imaging identified foveal injuries in 4 of these 8 patients (sensitivity, 50%), and 3 of these were identified as only partial tears. Dynamic CT identified instability of DRUJ in 6 of 8 patients (sensitivity, 75%). Seven of 8 patients had imaging findings suggestive of a foveal tear when including either MRI or CT imaging (sensitivity, 88%). Of the 4 patients with an intact foveal attachment on arthroscopy, 3 (specificity, 75%) had a stable DRUJ on CT and all 4 (specificity, 100%) had an intact foveal attachment on MRI. CONCLUSION: Sixty-two percent of patients with foveal tears on arthroscopy have a stable DRUJ on clinical examination. When combining MRI and dynamic CT imaging of the DRUJ, the sensitivity of detecting a foveal TFCC tear approaches 88% compared with a gold standard of wrist arthroscopy.

Biomechanical Stability of Diaphyseal Ulnar Shaft Fractures and Ulnar Shortening Osteotomies After Fixation.

BACKGROUND: To determine the amount of micromotion during forearm rotation after diaphyseal ulnar shaft fracture or osteotomy. METHODS: This was a biomechanical study using 7 paired-matched cadavers. The upper extremity was mounted in a custom rig and the forearm brought through full pronation and supination. A Hall effect sensor was placed at the fracture ends to measure micromotion for all tested conditions. There were 4 conditions tested: (1) intact ulnar shaft with plate to act as a control; (2) transverse fracture/osteotomy without stabilization; (3) fracture/osteotomy with cortical apposition stabilized with plate fixation; and (4) 50% comminuted fracture stabilized with plate. RESULTS: There was a significantly greater amount of fracture site motion in the fracture/osteotomy model without stabilization compared with all other tested conditions (P < .001, .0001, .0003, respectively). The fracture/osteotomy site with cortical apposition and the comminuted fracture models showed no statistically significant differences in the amount of micromotion compared with each another (P = .952) or compared with the intact ulnar shaft (P = .997, .889, respectively). CONCLUSIONS: There was no significant difference in the amount of motion between an intact ulnar shaft, an ulnar shaft fracture with cortical apposition stabilized with a plate, and a plated comminuted fracture. These findings may help surgeons decide on their type of postoperative immobilization in the setting of isolated ulnar shaft fractures or ulnar shaft osteotomies stabilized with plate fixation.

Investigation Into the Effects of Intra-Articular Steroid on Post-Traumatic Osteoarthritis in Distal Radius Fractures: A Randomized Controlled Pilot Study.

PURPOSE: The aim of this prospective, randomized, controlled, double-blinded pilot study was to determine the rates of post-traumatic osteoarthritis and assess joint space width in the presence or absence of a single intra-articular injection of corticosteroid after an acute, intra-articular distal radius fracture (DRF). METHODS: Forty patients received a single, intra-articular, radiocarpal joint injection of 4 mg of dexamethasone (DEX) (n = 19) or normal saline placebo (n = 21) within 2 weeks of a surgically or nonsurgically treated intra-articular DRF. The primary outcome measure was minimum radiocarpal joint space width (mJSW) on noncontrast computed tomography scans at 2 years postinjection. Secondary outcomes were obtained at 3 months, 6 months, 1 year, and 2 years postinjection and included Disabilities of the Arm, Shoulder, and Hand; Michigan Hand Questionnaire; Patient-Rated Wrist Evaluation; wrist range of motion; and grip strength. RESULTS: At 2-year follow-up, there was no difference in mean mJSW between the DEX group (2.2 mm; standard deviation, 0.6; range, 1.4-3.2) and the placebo group (2.3 mm; standard deviation, 0.7; range, 0.9-3.9). Further, there were no differences in any secondary outcome measures at any postinjection follow-up interval. CONCLUSIONS: Radiocarpal joint injection of corticosteroid within 2 weeks of an intra-articular DRF does not appear to affect the development of post-traumatic osteoarthritis within 2 years follow-up in a small pilot cohort. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic II.

Validation of the Clenched Fist View in Detecting Scapholunate Ligamentous Injury.

BACKGROUND: The purpose of this study was to determine the predictive value of the clenched fist stress views in identifying scapholunate ligament injuries. METHODS: An institutional review board-approved retrospective chart review was conducted of adult patients who underwent diagnostic arthroscopy with a ligamentous wrist injury from 2015 to 2020. Standard posteroanterior, lateral, and clenched fist stress radiographs were reviewed and scapholunate ligament gaps recorded. RESULTS: A total of 124 patients were included, of which 88 had normal standard radiographs and clenched fist radiographs. The positive predictive value of the clenched fist view was 69%, whereas the negative predictive value was 58%. The sensitivity of the clenched fist view was 40%, while the specificity was 82%. Of those patients with a negative clenched fist view, 42% were found to have an arthroscopic Geissler classification of 3 or higher scapholunate ligament injury. CONCLUSIONS: Despite the emphasis on stress radiographic views, a normal stress clenched fist view does not preclude arthroscopic findings of a Geissler class 3 or greater injury in symptomatic patients. The sensitivity of a clenched fist view is only 40%. These findings question the utility of stress radiographs when assessing for scapholunate ligament injuries.

Volar Wrist Arthroscopy Portals Using the NanoScope Are Safer than Traditional Arthroscopy.

BACKGROUND: The NanoScope, given its smaller size, may be further from critical structures when establishing volar wrist arthroscopy portals compared to the traditional 2.7-mm arthroscope. METHODS: Ten fresh-frozen latex-injected cadaver specimens were utilized. The volar radial (VR) and volar ulnar (VU) portals were created using an inside-out approach. The volar radial midcarpal (VR-MC) and volar ulnar midcarpal (VU-MC) portals were created using an inside-out approach. The arm was then dissected under 3.5-mm loupe magnification. Digital calipers were used to measure the distance between the portals and the surrounding anatomic structures by two fellowship-trained hand surgeons. RESULTS: The median nerve was on average 1.6, 7.2, 1.8, and 5.6 mm away from the trochar for the VR, VU, VR-MC, and VU-MC, respectively. The median nerve fascia was pierced by the VR portal in one specimen. The radial artery, ulnar artery, and ulnar nerve were not pierced in any specimen. Compared to historical controls, for the VR-MC portal, the NanoScope was further from all critical structures, aside from the radial artery, and did not pierce any neurovascular structures. For the VU-MC portal, the NanoScope was further from the ulnar artery and median nerve and did not pierce any neurovascular structures. CONCLUSION: In developing volar portals, after placing the cannula through the volar capsule from an inside-out approach, we recommend making a volar incision and dissecting the local anatomic structures to guard against injury. Compared to historical controls, the NanoScope was typically further from neurovascular structures.

Foveal triangular fibrocartilage complex pathology: a potentially under-recognized injury.

The primary aim of the present study was to present a case series of 24 patients with foveal triangular fibrocartilage complex (TFCC) injuries that were treated with arthroscopically assisted TFCC foveal repair. In total, 19 patients had a stable distal radioulnar joint (DRUJ) and five had an unstable DRUJ. Despite this, all patients were found to have a foveal tear upon DRUJ arthroscopy. Magnetic resonance imaging (MRI) scans detected only eight out of 23 patients with foveal injuries. In addition to their foveal injury, 19 of the 24 patients had additional pathology that required treatment. At a mean follow-up of 18 months, there was a statistically significant improvement in pain, range of motion, grip strength and functional scores. In this study, we demonstrate that having a stable DRUJ upon clinical examination and normal MRI findings does not rule out foveal TFCC injury and a high index of clinical suspicion is needed when managing patients with ulnar sided wrist pain.Level of evidence: IV.

Bilateral lunotriquetral coalition: a dynamic four-dimensional computed tomography technical case report.

Lunotriquetral coalitions are the most common form of carpal coalition wherein the cartilage between the lunate and triquetrum ossification centers failed to undergo apoptosis. This technical case report examines the arthrokinematics of bilateral lunotriquetral coalitions with dissimilar Minnaar types in one participant with one asymptomatic wrist and one wrist with suspected distal radioulnar joint injury. Static and dynamic (four-dimensional) CT images during pronosupination were captured using a photon-counting detector CT scanner. Interosseous proximity distributions were calculated between the lunotriquetral coalition and adjacent bones in both wrists to quantify arthrokinematics. Interosseous proximity distributions at joints adjacent to the lunotriquetral coalition demonstrate differences in median and minimum interosseous proximities between the asymptomatic and injured wrists during resisted pronosupination. Altered kinematics from lunotriquetral coalitions may be a source of ulnar-sided wrist pain and discomfort, limiting the functional range of motion. This case report highlights potential alterations to wrist arthrokinematics in the setting of lunotriquetral coalitions and possible associations with ulnar-sided wrist pain, highlighting anatomy to examine in radiographic follow-up. Furthermore, this case report demonstrates the technical feasibility of four-dimensional CT using photon-counting detector technology in assessing arthrokinematics in the setting of variant wrist anatomy.

Partial Denervation of the Thumb Carpometacarpal Joint: A New Technique.

BACKGROUND: To report the clinical outcomes of partial denervation for the treatment of basilar thumb joint arthritis. METHODS: Patients who underwent partial denervation of the basilar thumb joint for osteoarthritis from a single center between 2019 and 2021 were recruited into the study. This involved a technique that involved cauterization of the joint capsule and its innervation through the branches of the superficial radial, palmar cutaneous branch of the median, lateral antebrachial, and ulnar nerves. Patients were followed up postoperatively to record clinical (grip strength, thumb apposition and opposition pinch grip strength, Kapandji score) and patient-reported outcomes (visual analogue scale [VAS], Quick Disabilities of the Arm, Shoulder and Hand [QuickDASH], Patient-reported Wrist Evaluation [PRWE]). RESULTS: Twelve patients (15 carpometacarpal joints; 9 female and 3 male patients) underwent a partial denervation of the thumb (Eaton stage 3-4). The mean age at the time of surgery was 63 ± 5 years (range 56-72). The mean clinical follow-up duration was 23 ± 11 months (range 9-42 months), and functional score follow-up duration was 27 ± 7 months (range 14-42 months). At the latest clinical follow, VAS score, Kapandji score, grip strength, and thumb apposition/opposition pinch strength all improved significantly (P < .05). The mean QuickDASH score was 30 ± 16, and PRWE score was 32 ± 17. Patients who had unilateral partial thumb denervation demonstrated greater improvement in grip strength than patients who had bilateral partial thumb denervation procedures (P = .01). CONCLUSION: In this clinical case series, our method of basilar thumb joint partial denervation has been effective in improving clinical outcomes and reducing pain due to osteoarthritis. LEVEL OF EVIDENCE: IV, case series.

Innovations in Small Joint Arthroscopy.

With advancements in surgical instrumentation and techniques, the role of arthroscopic and arthroscopic-assisted surgical procedures is ever-growing. Arthroscopy offers direct, magnified visualization of pathology and reductions and is more accurate than relying on intraoperative fluoroscopy alone. It also minimizes soft tissue stripping, which is of particular importance to smaller fracture fragments whose vascularity is precarious and can be injured through open approaches.

Dorsal Subluxation of The Proximal Carpal Row with the Use of a Bridge Plate.

Background Spanning bridge plates were first popularized for fixation of complex distal radius fractures. However, indications for their use have expanded including the surgical treatment algorithm for treating conditions such as Kienböck's disease. Traditionally, initial surgical treatment of Lichtman Stages II to III Kienböck's disease included lunate decompression, unloading, and revascularization procedures. The addition of a dorsal spanning bridge plate further facilitates lunate offloading and may improve bone revascularization. Case Description We report a complication of proximal carpal row dorsal subluxation secondary to dorsal spanning plate fixation in a patient with Stage IIIb Kienböck's disease. The patient had undergone wrist arthroscopy, lunate forage, radius core decompression, and spanning plate fixation. At 6 weeks after surgery, radiographic imaging demonstrated dorsal subluxation of the proximal carpal row that was corrected upon bridge plate removal. Serial radiographs during follow-up showed no further carpal subluxation without Kienböck's disease progression at 12 months postremoval of hardware. Patient remains pain free and has returned to elite level sport. Literature Review To our knowledge no previous cases of proximal carpal row subluxation with the use of dorsal bridge plate has been reported in the literature. Clinical Relevance Proximal row carpal subluxation can occur with dorsal bridge plate fixation.

Clinical Outcomes of Arthroscopic-Assisted Volar Scapholunate Capsulodesis: A Case Series.

Purpose We have previously described arthroscopic-assisted volar scapholunate (SL) capsulodesis as an alternative technique for addressing volar SL interosseous ligament (SLIL) injuries. In this article, we report the outcomes of this procedure in a cohort of patients. Methods Postoperative outcomes including range of motion, grip strength, visual analog scale (VAS) pain score, Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH), and Mayo Wrist Score were assessed through a prospective review of six patients in a single center who underwent this procedure. Results Six patients (four male and two female) with a mean age of 43 ± 14 years were evaluated in the study. The mean duration of follow-up was 41 ± 17 weeks. Postoperative outcomes noted a reduction in VAS pain score from 8 before surgery to 0.7 postoperatively ( p = 0.00004) and improvement in Mayo Wrist Score (42 preoperatively to 80 postoperatively; p = 0.001), grip strength (86% of contralateral side; p = 0.20), and flexion arc (81% of contralateral side; p = 0.08). QuickDASH was 20 ± 8 and Patient-Rated Wrist Evaluation score was 13 ± 2 at the last clinical follow-up. There was an improvement in SL gap ( p = 0.03), SL angle ( p = 0.11), and radiolunate angle ( p = 0.15) measurements postoperatively. Conclusions The described arthroscopic-assisted volar SL capsulodesis in this study presents an alternative method to address volar SLIL pathology with positive short-term clinical outcomes. Clinical Relevance Arthroscopic-assisted volar SL capsulodesis may be considered in the treatment algorithm for volar SLIL injuries.

BMP2 and GDF5 for Compartmentalized Regeneration of the Scapholunate Ligament.

Background Chronic injuries to the scapholunate ligament (SLIL) alter carpal kinematics and may progress to early degenerative osteoarthritis. To date, there is no consensus for the best method for SLIL reconstruction. This study aims to assess the use of growth factors (bone morphogenetic protein [BMP]2 and growth and differentiation factor 5 [GDF5]) for compartmentalized regeneration of bone and ligament in this multiphasic scaffold in a rabbit knee model. Case Description A total of 100 µg of BMP2 and 30 µg of GDF5 were encapsulated into a heparinized gelatin-hyaluronic acid hydrogel and loaded into the appropriate compartment of the multiphasic scaffold. The multiphasic scaffold was implanted to replace the native rabbit medial collateral ligament ( n = 16). The rabbits were randomly assigned to two different treatment groups. The first group was immobilized postoperatively with the knee pinned in flexion with K-wires for 4 weeks ( n = 8) prior to sacrifice. The second group was immobilized for 4 weeks, had the K-wires removed followed by a further 4 weeks of mobilization prior to sample harvesting. Literature Review Heterotopic ossification as early as 4 weeks was noted on gross dissection and confirmed by microcomputed tomography and histological staining. This analysis revealed formation of a bony bridge located within and over the ligament compartment in the intra-articular region. Biomechanical testing showed increased ultimate force of the ligament compartment at 4 weeks postimplantation consistent with the presence of bone formation and higher numbers of scaffold failures at the bone-tendon junction. This study has demonstrated that the addition of BMP2 and GDF5 in the bone-ligament-bone (BLB) scaffold resulted in heterotopic bone formation and failure of the ligament compartment. Clinical Relevance The implantation of a three-dimensional-printed BLB scaffold alone demonstrated superior biomechanical and histological results, and further investigation is needed as a possible clinical reconstruction for the SLIL.