Innervation of the triangular fibrocartilage complex of the human wrist: Quantitative immunohistochemical study

Wrist proprioception-An update on scientific insights and clinical implications in rehabilitation of the wrist

The field of wrist proprioception, as it relates to rehabilitation and surgery, has gone through a period of intense growth in the past decade. From being primarily focused on the function of the joint and ligaments in patients with wrist trauma or after wrist surgery, the understanding is now that of a greater complexity in treating not just the wrist but the hand and arm as a whole. Proprioception is derived from the Latin words "proprius" - belonging to (oneself) and "-ception" to sense. In other words, how to sense ourselves. To have a complete sense of self, multiple sensory afferents originating from joints, ligaments, muscles, tendons, nerves, skin, vision, and hearing work together to orchestrate a balanced integration of sensorimotor functions, with the true goal to perceive and adapt to the physical world around us. In this update on wrist proprioception, we review current developments in the understanding of proprioception, with an implication for our everyday work as hand therapists and hand surgeons. Each contributing sense-joint, ligaments, muscles, skin, and brain-will be reviewed, and the clinical relevance will be discussed. An updated wrist rehabilitation protocol is proposed where the therapist is guided to rehabilitate a patient after wrist trauma and/or surgery in 4 stages: (1) basic hand and wrist rehabilitation with a focus on reducing edema, pain, and scar formation; (2) proprioception awareness to improve the sense of joint motion and position; (3) conscious neuromuscular rehabilitation where isometric exercises of muscles that are beneficial for a particular injury are promoted, whereas others that are potentially harmful are avoided; and (4) unconscious neuromuscular rehabilitation with training of the reflex and joint protective senses.

Ulnar Wrist Denervation: Articular Branching Pattern and Selective Blockade of the Dorsal Branch of the Ulnar Nerve

PURPOSE

Ulnar wrist denervation has been a successful treatment for patients with ulnar-sided wrist pain. The purpose of this study was to characterize the articular branches of the dorsal branch of the ulnar nerve (DBUN) and validate a technique for selective peripheral nerve blockade.

METHODS

In cadavers, we performed simulated local anesthetic injections using 0.5 mL of 0.5% methylene into the subcutaneous tissue at a point midway between the palpable borders of the pisiform and ulnar styloid. We then dissected the DBUN, characterized its articular branching pattern, and measured staining intensity of the DBUN and the ulnar nerve relative to a standard.

RESULTS

The DBUN branched from the ulnar nerve 7.0 ± 1.2 cm proximal to the ulnar styloid. Among 17 specimens, the DBUN provided an average of 1.2 (range, 0-2) ulnocarpal branches and 1.0 (range, 0-2) carpometacarpal articular branches. A simulated local anesthetic injection successfully stained 100% of the DBUN articular branches at or proximal to their takeoff. There was no staining of the proper ulnar nerves. In all specimens, the DBUN supplied at least one articular branch.

CONCLUSIONS

A point midway between the palpable border of the pisiform and ulnar styloid may be an effective location for selectively blocking the DBUN articular afferents.

CLINICAL RELEVANCE

In this study, we were able to identify a point halfway between the pisiform and ulnar styloid that has the potential to produce a selective peripheral nerve block of the portion of the DBUN that supplies articular fibers to the ulnocarpal joint and the fifth carpometacarpal joint. This technique may prove useful to surgeons treating ulnar-sided wrist pain.

Anatomical Study of the Innervation of Triangular Fibrocartilage Complex and Distal Radioulnar and Radiocarpal Joints: Implications for Denervation

PURPOSE

Open and percutaneous denervation is an emerging technique for joint pain. This study investigated the course and distribution of the articular branches innervating the triangular fibrocartilage complex (TFCC), distal radioulnar joint (DRUJ), and radiocarpal joint (RCJ) relative to bony and soft tissue landmarks to guide wrist denervation procedures.

METHODS

Fourteen formalin-embalmed specimens were serially dissected to expose the origin, course, and distribution of articular branches innervating the TFCC, DRUJ, and RCJ. Bony and soft tissue landmarks to localize each articular branch were documented and visualized on a 3-dimensional reconstruction of the bones of the distal forearm and hand.

RESULTS

The TFCC was innervated by articular branches from the posterior interosseus nerve (10 of 14 specimens), dorsal cutaneous branch of the ulnar nerve (14 of 14 specimens), palmar cutaneous branch of the ulnar nerve (12 of 14 specimens), and medial antebrachial cutaneous nerve (9 of 14 specimens). The DRUJ was innervated by the posterior interosseus nerve (9 of 14 specimens) and anterior interosseus nerve (14 of 14 specimens). The RCJ was innervated by the posterior interosseus nerve (14 of 14 specimens), superficial branch of the radial nerve (5 of 14 specimens), lateral antebrachial cutaneous nerve (14 of 14 specimens), and palmar cutaneous branch of the median nerve (10 of 14 specimens).

CONCLUSIONS

Multiple nerves were found to innervate the TFCC, DRUJ, and RCJ. The relationship of anatomical landmarks to specific articular branches supplying the TFCC, DRUJ, and RCJ can inform selective denervation procedures based on the structural origin of pain.

CLINICAL RELEVANCE

The detailed documentation of the spatial relationship of the nerve supply to the wrist provides clinicians with the anatomical basis to optimize current, and develop new denervation protocols to manage chronic wrist pain.

The Triangular Fibrocartilage Complex In The Human Wrist: A Scoping Review Towards Uniform And Clinically Relevant Terminology

The aim of this scoping review was to assess the composition, terminology, and anatomy of the triangular fibrocartilage complex (TFCC) of the wrist and propose unambiguous terminology regarding the individual components. The review was conducted according to the methodological framework by Arksey and O'Malley (International Journal of Social Research Methodology, 2005, 8, 19–32). Electronic databases were searched from inception until September 1, 2021 for original anatomical studies, using MeSH terms and keywords on terminology and anatomy of TFCC components. Studies using gross dissections or macro‐ or microscopic histology were included. Animal studies, fetal studies and studies with unknown disease status, were excluded. A total of 24 studies were included. The articular disc, the radioulnar ligaments, the meniscus homologue and the extensor carpi ulnaris tendon (sub)sheath were unanimously classified as TFCC components. One study did not include the ulnolunate and ulnotriquetral ligaments and only one study did include the ligamentum subcruentum. The largest disagreement existed regarding the inclusion of the ulnar collateral ligament. Terminological ambiguity was seen in “triangular fibrocartilage,” “triangular ligament,” “igamentum subcruentum,” and the “proximal and distal lamina.” Anatomical ambiguity existed especially regarding the radioulnar ligaments, the ulnar attachments of the TFCC and the ulnar collateral ligament. Definitions of the individual TFCC components are redundant, ambiguous, and ill‐defined and therefore subject to different interpretations. In order to preclude confusion, consensus regarding terminology is recommended. We proposed a concise definition of the healthy TFCC that can be used as a starting point for future studies and current clinical practice.

Ulnar Wrist Deviation in Children With Obstetric Brachial Plexus Palsy: A Descriptive Study of Clinical and Radiological Findings of Impaired Ulnar Growth and Associated Incongruence of the Distal Radioulnar Joint

Backround: Some children with obstetric brachial plexus palsy (OBPP) present later on with an ulnarly deviated wrist. The aim of this study was to present a retrospective analysis of a subgroup of OBPP children with ulnarly deviated wrists and to describe their morphologic wrist deformity in terms of clinical and radiological appearance. Methods: We present a retrospective analysis of the records of 27 children with an ulnarly deviated wrist as a consequence of OBPP. Radiographs of the affected wrist were performed when the ulnar deformity became clinically manifest and merited investigation, at a mean age of 15 (range: 6.5-27) years. Available clinical and radiological data were analyzed and categorized. Results: The ulnar-deviated position was associated with impaired active and passive pronosupination in all patients. Fifteen fixed supination deformities and 3 anterior radial head dislocations were noted clinically. Plain radiographs were completed in 24 patients and could be analyzed in 18, showing variations in ulnar variance (7 neutral, 7 ulna minus, and 4 ulna plus) along with 6 subluxations of the distal radioulnar joint (DRUJ). Of the patients treated surgically (n = 7), only the 2 patients treated with wrist fusion had an actual improvement in ulnar wrist deformity. Conclusion: Radiologically visible ulnar head hypoplasia, overgrowth of the distal ulna, or a shortened ulnar diaphysis and an incongruent DRUJ were present in all examined OBPP patients with a clinically evident ulnarly deviated wrists. The radiological findings highlight the morphologic adaptation behind this clinical condition and could allow further investigation into suitable treatment strategies.

What Is the Effect of the Ulnar-Plus Variance on the Outcomes of Arthroscopic Repair of the Peripheral Ulnar-Side Triangular Fibrocartilage Complex Tear?

PURPOSE

To compare the outcomes of arthroscopic repair of peripheral ulnar-side triangular fibrocartilage complex (TFCC) tears between patients with and without ulnar-plus variance (UPV) and to identify factors associated with index surgery failure in these patients.

METHODS

We retrospectively analyzed 50 consecutive patients who underwent arthroscopic repair of peripheral ulnar-side TFCC tears from June 2014 to February 2018. We selected patients who were aged at least 18 years and underwent arthroscopic repair of peripheral ulnar-side TFCC tears. We excluded those with a fractured or dislocated wrist, ulnar impaction syndrome, degenerative or inflammatory arthritis of the wrist, or neurologic conditions that affect upper-extremity function, as well as those who received less than 12 months' follow-up. We evaluated the patients with a visual analog scale for pain in 3 domains (overall, with hard work, and at rest), the Patient-rated Wrist Evaluation, range of motion, and grip strength. Clinical outcomes and arthroscopic findings were compared between patients with and without UPV (UPV group and non-UPV group, respectively). We calculated the relative risk and 95% confidence interval for younger age (<30 years), sex, UPV, and coexisting degenerative central TFCC tear (type 2 tear) to determine the risk factors for arthroscopic repair failure.

RESULTS

No significant differences were noted between the 2 groups regarding visual analog scale pain and Patient-rated Wrist Evaluation scores and rates of excellent or improved outcomes (P > .05). Arthroscopic repair failure was found in 4 patients. A coexisting type 2 TFCC tear was the only significant risk factor (relative risk, 49.5; 95% confidence interval, 2.94-83.96; P = .007) for arthroscopic repair failure.

CONCLUSIONS

UPV did not significantly affect the outcomes of arthroscopic repair of peripheral ulnar-side TFCC tears. However, coexisting type 2 TFCC tears significantly increased the risk of index surgery failure in these patients.

LEVEL OF EVIDENCE

Level IV, prognostic study.

Distribution, quantity and gene expression of mechanoreceptors in ligaments and tendons of knee joint in rabbits

Here we investigated the morphology, quantity, distribution and gene expression of mechanoreceptors in the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), lateral collateral ligament (LCL), patellar tendon (PaT) and popliteal tendon (PoT) of the knee joint. Twelve 6-month-old rabbits were divided into two groups. In one group, the ACL, PCL, MCL, LCL, PaT and PoT were collected to observe the morphology, distribution and quantity of mechanoreceptors. In another group, the ACL, PCL, MCL, LCL, PaT and PoT of bilateral knee joints were used to determine S100B, CGRP and NEFM gene levels. Five types of mechanoreceptors were observed including Ruffini corpuscles, Pacinian corpuscles, Golgi-tendon bodies, atypical mechanoreceptors and free nerve endings. The total amount of mechanoreceptors was significantly lower in MCL, LCL, PaT and PoT as compared with ACL and PCL (P < 0.001). All examined mechanoreceptors were present in ACL, PCL and LCL. However, no Pacinian corpuscles and Golgi-tendon bodies were found in MCL and PoT as well as Pacinian corpuscles were not observed in PaT. The present study indicated that the levels of NEFM was significantly lower in PCL, MCL, LCL, PaT and PoT as compared with ACL (P < 0.05), but there was no significant difference in CGRP level between ACL and other ligaments except LCL (P > 0.05). Thus, the quantity, type and gene expression of mechanoreceptors are different in various ligaments. Thus, the quantity and distribution of mechanoreceptors may be related to ligament's function.

Arthroscopic electrothermal collagen shrinkage for partial scapholunate ligament tears, isolated or with associated triangular fibrocartilage complex injuries: a prospective study

BACKGROUND

To present the outcomes of arthroscopic electrothermal shrinkage for partial scapholunate (SL) ligament tears, isolated or with associated triangular fibrocartilage complex (TFCC) injuries.

METHODS

A prospective study of 20 patients with symptomatic instability of SL ligament (14 of them also with TFCC wrist injuries) treated with arthroscopic electrothermal shrinkage was conducted using a monopolar radiofrequency probe. No patient showed radiologic signs of static dissociation (mean SL interval 2.2 ± 0.6 mm; mean SL angle 41.4° ± 6.7°) before surgery. All patients underwent follow-up at our clinic regularly for an average of 50.6 months (range 29-80 months).

RESULTS

The modified Mayo wrist score improved from a mean of 59 ± 17.1 points preoperatively to 88.3 ± 16.2 points at the final follow-up. At the final clinical examination, a painful Watson scaphoid shift test was found in 3 patients (15%). The mean flexion-extension arc was unchanged (132° ± 19°), and mean grip strength improved 12 kg. No patient showed radiologic signs of arthritis or instability after surgery (mean SL interval 1.9 ± 0.7 mm; mean SL angle 42.7° ± 7.3°). Of the 14 patients with combined TFCC injuries, 3 patients continued complaining of ulnar-sided point tenderness. At the end of the follow-up, 80% of the subjects were satisfied or very satisfied.

CONCLUSIONS

SL ligament and TFCC electrothermal shrinkage effectively provided pain relief and grip strength increase for most of the patients treated.

LEVEL OF EVIDENCE

Level IV.

The Effect of Triangular Fibrocartilage Complex Tear on Wrist Proprioception

PURPOSE

This study examined the influence of triangular fibrocartilage complex (TFCC) deep fiber tears on wrist proprioception.

METHODS

The study involved 48 subjects: 24 with deep fiber TFCC tears and 24 with healthy wrists. A specially created sensor measured wrist proprioception in 3 axes of movement. Absolute differences between target and subject-reproduced angles were compared in injured and healthy wrists and in injured and contralateral patient wrists. A greater difference in reproduced angles was deemed to reflect a lesser ability to approximate a target angle.

RESULTS

In wrists with TFCC injuries, 40° pronation and 60° pronation showed significantly greater differences between target and subject-reproduced angles compared with those in the control wrists. In wrists with TFCC injuries, 40° pronation demonstrated significantly greater differences between target and subject-reproduced angles than did those in patients' contralateral wrists. Proportions of outliers with absolute differences greater than 6° were significantly higher in 60° supination and 40° pronation in wrists with TFCC injuries.

CONCLUSIONS

Deep TFCC fiber detachment may lead to decreased wrist proprioception in 60° and 40° forearm rotation.

CLINICAL RELEVANCE

Deep TFCC fiber tear may contribute to decreased wrist rotational positioning sense and may have biomechanical importance in distal radioulnar joint stability.

Effect of Electrothermal Treatment on Nerve Tissue Within the Triangular Fibrocartilage Complex, Scapholunate, and Lunotriquetral Interosseous Ligaments

PURPOSE

To evaluate the effect of thermal treatment on neural tissue in the triangular fibrocartilage complex (TFCC), scapholunate interosseous ligament (SLIL), and lunotriquetral interosseous ligament (LTIL).

METHODS

The intact TFCC, SLIL, and LTIL were harvested from cadaveric specimens and treated with a radiofrequency probe as would be performed intraoperatively. Slides were stained using a triple-stain technique for neurotrophin receptor p75, pan-neuronal marker protein gene product 9.5 (PGP 9.5), and 4',6-diamidino-2-phenylindole for neural identification. Five TFCC, 5 SLIL, and 4 LTIL specimens were imaged with fluorescence microscopy. Imaging software was used to measure fluorescence signals and compare thermally treated areas with adjacent untreated areas. A paired t test was used to compare treated versus untreated areas. P < .05 was considered significant.

RESULTS

For the TFCC, a mean of 94.9% ± 2.7% of PGP 9.5-positive neural tissue was ablated within a mean area of 11.7 ± 2.5 mm(2) (P = .02). For the SLIL treated from the radiocarpal surface, 97.4% ± 1.0% was ablated to a mean depth of 2.4 ± 0.3 mm from the surface and a mean horizontal spread of 3.4 ± 0.5 mm (P = .01). For the LTIL, 96.0% ± 1.5% was ablated to a mean depth of 1.7 ± 0.7 mm and a mean horizontal spread of 2.6 ± 1.0 mm (P = .02). Differences in the presence of neural tissue between treated areas and adjacent untreated areas were statistically significant for all specimens.

CONCLUSIONS

Our study confirms elimination of neuronal markers after thermal treatment of the TFCC, SLIL, and LTIL in cadaveric specimens. This effect penetrates below the surface to innervated collagen tissue that is left structurally intact after treatment.

CLINICAL RELEVANCE

Electrothermal treatment as commonly performed to treat symptomatic SLIL, LTIL, and TFCC tears eliminates neuronal tissue in treated areas and may function to relieve pain through a denervation effect.

Immunohistochemical Mapping of Sensory Nerve Endings in the Human Triangular Fibrocartilage Complex

BACKGROUND

The triangular fibrocartilage complex is the main stabilizer of the distal radioulnar joint. While static joint stability is constituted by osseous and ligamentous integrity, the dynamic aspects of joint stability chiefly concern proprioceptive control of the compressive and directional muscular forces acting on the joint. Therefore, an investigation of the pattern and types of sensory nerve endings gives more insight in dynamic distal radioulnar joint stability.

QUESTIONS/PURPOSES

We aimed to (1) analyze the general distribution of sensory nerve endings and blood vessels; (2) examine interstructural distribution of sensory nerve endings and blood vessels; (3) compare the number and types of mechanoreceptors in each part; and (4) analyze intrastructural distribution of nerve endings at different tissue depth.

METHODS

The subsheath of the extensor carpi ulnaris tendon sheath, the ulnocarpal meniscoid, the articular disc, the dorsal and volar radioulnar ligaments, and the ulnolunate and ulnotriquetral ligaments were dissected from 11 human cadaver wrists. Sensory nerve endings were counted in five levels per specimen as total cell amount/cm(2) after staining with low-affinity neurotrophin receptor p75, protein gene product 9.5, and S-100 protein and thereafter classified according to Freeman and Wyke.

RESULTS

All types of sensory corpuscles were found in the various structures of the triangular fibrocartilage complex with the exception of the ulnolunate ligament, which contained only Golgi-like endings, free nerve endings, and unclassifiable corpuscles. The articular disc had only free nerve endings. Furthermore, free nerve endings were the predominant sensory nerve ending (median, 72.6/cm(2); range, 0-469.4/cm(2)) and more prevalent than all other types of mechanoreceptors: Ruffini (median, 0; range, 0-5.6/cm(2); difference of medians, 72.6; p < 0.001), Pacini (median, 0; range, 0-3.8/cm(2); difference of medians, 72.6; p < 0.001), Golgi-like (median, 0; range, 0-2.1/cm(2); difference of medians, 72.6; p < 0.001), and unclassifiable corpuscles (median, 0; range, 0-2.5/cm(2); difference of medians, 72.6; p < 0.001). The articular disc contained fewer free nerve endings (median, 1.8; range, 0-17.8/cm(2)) and fewer blood vessels (median, 29.8; range, 0-112.2/cm(2); difference of medians: 255.9) than all other structures of the triangular fibrocartilage complex (p ≤ 0.001, respectively) except the ulnolunate ligament. More blood vessels were seen in the volar radioulnar ligament (median, 363.62; range, 117.8-871.8/cm(2)) compared with the ulnolunate ligament (median, 107.7; range, 15.9-410.3/cm(2); difference of medians: 255.91; p = 0.002) and the dorsal radioulnar ligament (median, 116.2; range, 53.9-185.1/cm(2); difference of medians: 247.47; p = 0.001). Free nerve endings were obtained in each structure more often than all other types of sensory nerve endings (p < 0.001, respectively). The intrastructural analysis revealed no differences in mechanoreceptor distribution in all investigated specimens with the numbers available, showing a homogenous distribution of proprioceptive qualities in all seven parts of the triangular fibrocartilage complex.

CONCLUSIONS

Nociception has a primary proprioceptive role in the neuromuscular stability of the distal radioulnar joint. The articular disc and ulnolunate ligament rarely are innervated, which implies mainly mechanical functions, whereas all other structures have pronounced proprioceptive qualities, prerequisite for dynamic joint stability.

CLINICAL RELEVANCE

Lesions of the volar and dorsal radioulnar ligaments have immense consequences not only for mechanical but also for dynamic stability of the distal radioulnar joint, and surgical reconstruction in instances of radioulnar ligament injury is important.

Update TFCC: histology and pathology, classification, examination and diagnostics

The TFCC is a crucial stabilizer of the DRUJ. Based on its superficial and deep fibers, the TFCC guarantees unrestricted pronation and supination which is essential for performing sophisticated tasks. The ability to perform complex movements is of uppermost importance for hand function. Therefore, a functional intact TFCC is a prerequisite in this context. The articular disc of the TFCC is a fibrocartilaginous extension of the superficial zone of hyaline articular cartilage which arises from the radius. The peripheral 10-40 % of the TFC is vascularized. Degeneration of the articular disc is common with increasing age. Even though the central part of the articular disc is avascular, potential regeneration of lesions could be detected. The Palmer and Atzei classifications of TFCC lesions are complementary. TFCC innervation is based on different nerves. There is a high variability. A diligent clinical examination facilitates specific tests which help to allocate symptoms to the pathology. Therefore, a thorough clinical examination is not dispensable. Wrist arthroscopy remains the "gold standard" for diagnosing TFCC pathologies despite technical progress in imaging modalities. MR arthrography may have the potential to become a real alternative to wrist arthroscopy for diagnosing TFCC pathologies with technical progress in the future.

Sensory innervation of the triangular fibrocartilage complex: a cadaveric study

PURPOSE

To describe the sensory innervation of the triangular fibrocartilage complex (TFCC) to understand the potential for selective denervation as an alternative treatment for recalcitrant pain from stable TFCC IA lesions after failed nonsurgical treatment.

METHODS

Eleven fresh cadaveric limbs were dissected with × 3.2 loupe magnification in a proximal to distal manner. The candidate nerves were the dorsal cutaneous branch of the ulnar nerve, volar sensory branch of the ulnar nerve, anterior interosseous nerve, posterior interosseous nerve, medial antebrachial cutaneous nerve, and palmar cutaneous branch of the median nerve. We identified neural continuity to the TFCC histologically with S-100 protein antibody staining.

RESULTS

In the 11 specimens, the TFCC was innervated by the dorsal cutaneous branch of the ulnar nerve (100%), medial antebrachial cutaneous nerve (91%), volar branch of the ulnar nerve (73%), anterior interosseous nerve (27%), posterior interosseous nerve (18%), and palmar branch of the median nerve (9%).

CONCLUSIONS

These results provide an initial step in planning an operative partial TFCC denervation for recalcitrant TFCC IA injuries that fail nonsurgical treatment and possibly also arthroscopic debridement.

CLINICAL RELEVANCE

Based on the results of this anatomic study, it is possible to create an algorithm for performing nerve blocks of the TFCC that would aid in planning a surgical denervation procedure.

Clinical, radiographic, and arthroscopic outcomes after ulnar shortening osteotomy: a long-term follow-up study

PURPOSE

Previous studies have investigated the long-term outcomes of ulnar shortening osteotomy (USO) in the treatment of ulnocarpal abutment syndrome (UCA), but none have used arthroscopic assessments. The purpose of this study was to investigate the long-term clinical outcomes of USO with patient-based, arthroscopic, and radiographic assessments.

METHODS

We retrospectively reviewed 30 patients with UCA after a minimum follow-up of 5 years, with arthroscopic evaluations at the time of both USO and plate removal. We confirmed the initial diagnosis of UCA by radiography and arthroscopy. Mean age at the time of index surgery was 37 years. Mean duration of follow-up was 11 years (range, 5-19 y). We obtained Disabilities of the Arm, Shoulder, and Hand and Hand20 self-assessments postoperatively for all patients. Bony spur formation was evaluated postoperatively from plain radiographs.

RESULTS

We detected triangular fibrocartilage complex (TFCC) disc tear in 13 wrists arthroscopically at the time of USO. Of these, 10 showed no evidence of TFCC disc tear at second-look arthroscopy. The remaining 17 cases showed no TFCC disc tear at either first- or second-look arthroscopy. Follow-up radiography revealed that bony spurs at the distal radioulnar joint had progressed in 13 wrists. Disabilities of the Shoulder, Arm, and Hand and Hand20 scores did not significantly correlate with the presence of bony spurs or TFCC disc tears. Range of motion decreased significantly with age only. Lower grip strength correlated with bony spur and lower radial inclination. Triangular fibrocartilage complex tear, male sex, and advanced age were associated with lower Disabilities of the Shoulder, Arm, and Hand and Hand20 scores.

CONCLUSIONS

Ulnar shortening osteotomy achieved excellent long-term results in most cases. Most TFCC disc tears identified at the initial surgery had healed by long-term arthroscopic follow-up. We suggest that UCA with a TFCC disc tear is a good indication for USO.

Development and morphogenesis of human wrist joint during embryonic and early fetal period

The development of the human wrist joint has been studied widely, with the main focus on carpal chondrogenesis, ligaments and triangular fibrocartilage. However, there are some discrepancies concerning the origin and morphogenetic time-table of these structures, including nerves, muscles and vascular elements. For this study we used serial sections of 57 human embryonic (n = 30) and fetal (n = 27) specimens from O'Rahilly stages 17-23 and 9-14 weeks, respectively. The following phases in carpal morphogenesis have been established: undifferentiated mesenchyme (stage 17), condensated mesenchyme (stages 18 and 19), pre-chondrogenic (stages 19 and 20) and chondrogenic (stages 21 and over). Carpal chondrification and osteogenic processes are similar, starting with capitate and hamate (stage 19) and ending with pisiform (stage 22). In week 14, a vascular bud penetrates into the lunate cartilaginous mold, early sign of the osteogenic process that will be completed after birth. In stage 18, median, ulnar and radial nerves and thenar eminence appear in the hand plate. In stage 21, there are indications of the interosseous muscles, and in stage 22 flexor digitorum superficialis, flexor digitorum profundus and lumbrical muscles, transverse carpal ligament and collateral ligaments emerge. In stage 23, the articular disc, radiocarpal and ulnocarpal ligaments and deep palmar arterial arch become visible. Radiate carpal and interosseous ligaments appear in week 9, and in week 10, dorsal radiocarpal ligament and articular capsule are evident. Finally, synovial membrane is observed in week 13. We have performed a complete analysis of the morphogenesis of the structures of the human wrist joint. Our results present new data on nervous and arterial elements and provide the basis for further investigations on anatomical pathology, comparative morphology and evolutionary anthropology.

Nerve fiber staining investigations in traumatic and degenerative disc lesions of the wrist

PURPOSE

Traumatic and degenerative disc lesions cause ulnar-sided wrist pain. To date, anatomical investigations of cadaver triangular fibrocartilage discs examining the innervation of the triangular fibrocartilage complex have found no evidence of nerve fibers in the healthy disc. In this study, we immunohistologically investigated biopsies from patients with either central traumatic or degenerative disc lesions, to determine the existence of nerve fibers. We hypothesized that an ingrowth of nerve fibers causes ulnar-sided wrist pain associated with traumatic and degenerative disc lesions.

METHODS

We included 32 patients with a traumatic Palmer 1A lesion and 17 patients with a degenerative Palmer 2C lesion in the study. We obtained a biopsy of each patient and stained the specimen with protein gene product 9.5 for nerve fiber detection.

RESULTS

There were no nerve fibers in either traumatic or degenerative disc lesions. In addition, the marginal areas of the biopsies showed no evidence of nerve fibers.

CONCLUSIONS

Traumatic and degenerative disc lesions show no ingrowth of nerve fibers.

Surgical approaches to the distal radioulnar joint

For the distal radioulnar joint (DRUJ) to be stable, not only do the articulating surfaces need to be congruent and well aligned but also the capsule and ligaments need to be mechanically and sensorially competent. According to recent investigations, ligaments should not be regarded as simple static structures maintaining articular alignment but as complex arrangements of collagen fibers containing mechanoreceptors, which are able to generate neural reflexes aiming at a more efficient and a more definitive muscular stabilization. By careful planning and meticulous execution of surgical incisions to approach the DRUJ, the nerve endings innervating the capsule and DRUJ ligaments may be safeguarded, thus preserving the proprioceptive function of the joint.

Understanding stability of the distal radioulnar joint through an understanding of its anatomy

The authors describe the anatomy of the distal radioulnar joint (DRUJ) and delineate the importance of viewing this joint as part of the whole forearm. The osseous congruity and ligamentous integrity is of essence for the stability of the DRUJ, according to the principles of tensegrity. The neuromuscular control and possible proprioceptive function of the DRUJ are also outlined.

Role of low-affinity nerve growth factor receptor inhibitory antibody in reducing pain behavior and calcitonin gene-related Peptide expression in a rat model of wrist joint inflammatory pain

PURPOSE

Nerve growth factor (NGF), via the high-affinity receptor, tyrosine kinase A, has been widely reported as a mediator of pain caused by inflammation. A clinical trial has suggested that anti-NGF antibody is effective for pain caused by osteoarthritis of the knee. However, adverse events such as headache (8.9%), upper respiratory tract infection (7.3%), and paresthesia (6.8%) were reported. We hypothesized that inhibition of the low-affinity NGF receptor, p75 neurotrophin receptor (p75NTR), is also effective for joint pain and may reduce side effects. This study examined suppression of pain behavior and expression of pain-inducing neuropeptides such as calcitonin gene-related peptide (CGRP) and p75NTR in dorsal root ganglia neurons by a p75NTR inhibitory antibody in a rat model of wrist joint inflammatory pain.

METHODS

We injected complete Freund's adjuvant (CFA) into the wrist joint of rats and used this as a model of inflammatory pain. We applied 10 microL of saline (CFA + saline group; n = 20) or 1, 10, or 50 microL of a p75NTR inhibitory antibody (CFA + p75NTR inhibitory antibody group; n = 40) directly to the inflamed joint in the rats. Mechanical hyperalgesia was measured for 2 weeks using von Frey filaments. We assessed CGRP and p75NTR expression in C8 dorsal root ganglia immunochemically. Adverse events such as loss of weight and/or appetite, constipation, and infection were examined.

RESULTS

p75NTR inhibitory antibody reduced mechanical hyperalgesia caused by CFA (p<.05 vs controls) in the rat model (p<.01 vs saline), without any adverse events. We found that 10 and 50 microL of a p75NTR inhibitory antibody were more effective for pain, without a significant difference between doses. CGRP and p75NTR immunoreactivity was upregulated in the CFA + saline groups compared with a control group (p<.01). However, direct p75NTR inhibitory antibody application decreased CGRP and p75NTR expression after wrist inflammation (p<.01).

CONCLUSIONS

p75NTR inhibition may be a therapeutic target for inflamed joint pain treatment with reduced adverse events.