Unstable Joint Research Articles

Mini-Screw Fixation for the Treatment of Proximal Interphalangeal Joint Dorsal Fracture–Dislocations

Surgical intervention may be necessary to treat unstable dorsal fracture-dislocations of the proximal interphalangeal (PIP) joint of the hand. One method of stabilization is open reduction and internal fixation (ORIF). The purpose of this study was to assess the outcomes of ORIF for unstable dorsal fracture-dislocations of the PIP joint using mini-screws via a volar approach. A retrospective chart review with clinical follow-up evaluation was performed on 9 patients who had ORIF for unstable dorsal fracture-dislocations of the PIP joint. The fracture fragment(s) from the middle phalangeal base were reduced and secured using mini-screws. A clinical evaluation was performed at an average of 42 months after surgery. The average arc of motion for the involved PIP joint was 70 degrees (range, 55 degrees -90 degrees ). The average PIP joint motion in the 2 patients with 1 fracture fragment was 85 degrees , and the average PIP joint motion for the remaining 7 patients was 65 degrees . One joint was subluxated with an intra-articular screw. Nine patients had an average flexion contracture of 14 degrees . Seven patients had no pain, and 2 had pain only with heavy activity. Open reduction and internal fixation of unstable dorsal PIP joint fracture-dislocations using mini-screws can be considered if the fracture fragment(s) can accommodate the screws. The procedure attempts to restore the concave contour of the middle phalangeal base and permits early protected range of motion. The procedure should be approached cautiously, especially in the presence of comminution. Proximal interphalangeal joint range of motion is usually compromised; 8 of our 9 joints had a residual flexion contracture. Therapeutic IV.

Cost-Effective Optoelectronic Packages Using Powder Metallurgy

In this paper, we propose powder metallurgy for optoelectronic packages in order to reduce the cost of laser packages. Conventional die compaction (DC) and metal injection molding (MIM) are used for the shaping of powder metallurgy. The distinguishing types of inherent porosity in DC and MIM steels have their respective effects on the defect mechanisms of laser welding joints. For DC steel with 85% relative density and continuous porosity, the rising gas pressure pushes the molten metal out of the welding regions, resulting in weak and unstable welding joints. For MIM steel with more than 95% relative density, the laser power dominates the defect mechanisms, and the defect-free welding joints with optical spot size of 400 mum can be attained by using laser power of less than 1.0 kW. Although elimination of inherent porosity in MIM steel under optimum welding condition can give rise to additional postwelding-shift (PWS), it is still controlled to less than 2 mum, resulting in optical coupling loss of less than 15%. The advantage of applicability of the MIM method to several materials makes it possible to employ SS316L, Kovar, and Invar, which have the characteristic of better property for laser welding but difficult machining, as the metal housing in low-cost lightwave communication system. Thus, using MIM Invar with low coefficient of thermal expansion can minimize the tracking error, which is an important issue for bidirectional and triple-directional optoelectronic packages. The reliability data demonstrate that the laser modules using MIM steel as construction housing are stable and reliable

Dorsal calcaneocuboid ligament versus lateral ankle ligament repair: a case-control study

Objective: Anatomic reconstruction is the treatment of choice for lateral ankle ligament instability. A similar technique has recently been described for stabilisation of a chronic unstable calcaneocuboid joint as an...

Study on the weldability of stainless steel fabricated by powder metallurgy and metal injection molding for optoelectronic packages

To reduce the cost of optoelectronic modules, powder metallurgy (PM) and metal injection molding (MIM) are employed to fabricate metal housings for optoelectronic packages. During the laser welding of PM steel, the rising gas pressure pushes the molten metal out of the welding regions, resulting in weak and unstable joints. Metal parts fabricated by the MIM method provide good weldability, shape complexity, low cost, and long-term reliability. By using the MIM method, defect-free welding joints and postwelding-shifts of less than 1 µm are achieved, and the optoelectronic packages are reliable. Employment of MIM not only gives optoelectronic module designers more design flexibility due to the advantage of shape complexity, but also makes low-cost triple-directional optoelectronic modules realizable.

계단 오르기와 내리기 동안 다축범위(multi-radius) 무릎인공관절 수술자의 운동역학적 비교분석

The primary purpose of a TKA is to restore normal knee function Therefore, ideally, a TKA should: (a) maintain the natural leverage of the knee joint muscles to ensure generating adequate knee muscle moments to accomplish daily tasks such as rising from climbing stairs; (b) provide adequate knee joint stability. A 16-channel MyoResearch XP EMG system was used to collect the differential input surface electromyography signals VM, VL, RF, BF, ST during climbing/descending stair tests. A Peak Motion Measurement System was used to collect the kinematic and kinetic data. AKIN-COM Ill isokinetic dynamometer was used for EMG of VM, VL, RF, BF and ST during maximal voluntary contraction. I Quadriceps EMG results for the VM of the passed 1year group limb demonstrated significant less RMS EMG than that of the passed 3year group limb <TEX>$60^{\circ}-15^{\circ}$</TEX> of knee flexion(p<0.05). The VL of the passed 1year group limb also demonstrated significants less RMS EMG than that of the passed 3year group limb from <TEX>$60^{\circ}-45^{\circ}$</TEX> of knee flexion(p<0.05). Similar to the VM and VL, the RF of the passed 1year group limb showed less RMS EMG than that of the passed 3year group limb from <TEX>$60^{\circ}-30^{\circ}$</TEX> do knee flexion(p<0.05). Hamstring EMG results for the BF of the passed 1year group limb demonstrated less RMS EMG than that of the passed 3year group limb from <TEX>$75^{\circ}-15^{\circ}$</TEX> of knee flexion(p<0.05). The passed 1year group limb tended to have less ADD displacement(p<0.071) than that of the passed 3year group limb. There was no significant difference of the ABD displacement between the passed 1year group and the passed 3year group limbs(p<0.73). The passed 3year group used compensatory adaptation movement strategies to compensate for the strength deficit of passed 3year group limbs. The passed 3year group limb also increased the quadriceps muscle activation level to produce more knee extension moment to compensate for the short quadriceps moment arm. The passe 3year group limb might have an unstable knee joint in the medio-Iateral direction during the climbing/descending by showing a tendency of more ADD displacement and greater hamming co-activation EMG than the passed 1year group limbs. The TKA design was not able to help the knee joint to produce adequate knee extension moment with less quadriceps muscle effort. I think that old man needs continuous exercise for muscle strength.

Properties and failure mechanisms of pinned composite lap joints in monotonic and cyclic tension

The effect of through-thickness reinforcement by fibrous pins on the static tensile strength, fatigue life and failure mechanisms of single lap joints made of carbon/epoxy composite is investigated. Pinning is highly effective in increasing the ultimate strength, elongation limit and fatigue life. Improvements to the monotonic and fatigue properties are attributed to transitions in the failure mechanisms, from unstable joint debonding in the absence of pins to stable debonding in the presence of pins followed by ultimate failure by pin pull-out or shear fracture or tensile laminate rupture. Which mechanism induces ultimate failure in the presence of pins depends on their volume content and diameter. The trends with volume content and diameter can be predicted qualitatively using analytical results from a previously published model of the deformation mechanics of pins loaded in mixed mode.

Étude électromyographique des réflexes d’étirement intervenant au niveau de l’articulation coxo-fémorale normale et prothétique

Purpose of the study Several studies have been devoted to the effect of proprioception on joint function. Modifications in feedback control from the cord have been observed in unstable joints due to capsule and ligament laxity. A few studies have examined the effect of knee and hip arthroplasty on proprioception, but none have established whether stretch reflexes affect function of a prosthetic joint. The purpose of the present study was to demonstrate the electromyographic characteristics of stretch reflexes of the normal hip joint and to compare them with those observed in the prosthetic hip. Material and methods Two groups of patients were studied. The first included eleven subjects free of neurological disorders whose studied limb was healthy. The second group included ten subjects with a total hip prosthesis who had undergone extensive capsulectomy during the arthroplasty. Voluntary muscle contraction was noted in each subject. In addition, electromyographic recordings were made to note response of the ipsilateral and contralateral quadriceps crural and tensor of the fascia lata during changes in joint position. Recordings were made with the subject in the supine position, the limb suspended, hip flexed at 45̊ and knee extended. Three series of ten recordings were made in random order to measure the latency of muscle response to free fall of the limb, accelerated fall of the relaxed limb, and accelerated fall associated with calibrated contraction of the quadriceps. Mean latency of muscle response was calculated for each trial. Results In the conditions of this study, there was no statistically significant difference (p = 0.05) in the reflex time course between natural and prosthetic hips. Discussion Changes due to joint replacement and capsulectomy do not appear to affect the stretch reflexes of the hip joint.

Management of tophaceous gout of the distal interphalangeal joint

Surgical management of acute tophaceous gout of the distal interphalangeal joint is often associated with delayed wound healing. Aspiration through neighbouring uninvolved skin is a safe method of treating these tophi. For persistently symptomatic, unstable DIP joints, arthrodesis should be considered.

Prolotherapy (Proliferation Therapy) in the Treatment of TMD

Proliferation therapy, or “prolotherapy,” is also known as regenerative injection therapy (RIT). Since the 1930s, the technique has been used to stabilize injured joints and to relieve joint pain. This article reviews the history and scientific literature regarding prolotherapy and describes the application of the technique to treat injured or unstable temporomandibular joints (TMJ). Alternative medicaments and the likely mechanisms of action are discussed. A brief preliminary summary of a retrospective clinical study of the efficacy of prolotherapy is included. The study shows that prolotherapy can be an effective therapeutic modality that reduces TMJ pain and joint noise in a majority of patients who have reached a plateau with use of an intraoral appliance, physical therapy, and home care.

Distal Radius Fractures: A Comparison of Tension Band Wiring Versus Ulnar Outrigger External Fixation for the Management of Distal Radioulnar Instability

To retrospectively compare the results of immobilization of the forearm in supination with the results of tension band fixation of the ulnar styloid in 35 patients with distal radius fractures, fracture of the base of the ulnar styloid, and distal radioulnar joint instability treated with external fixation. Thirty-five patients with fractures of the distal radius, fracture of the base of the ulnar styloid, and unstable distal radioulnar joint had external fixation with adjunctive percutaneous pins and allograft bone to reduce and stabilize the distal radius fracture anatomically. Only those patients with an associated ulnar styloid base fracture displaced over 2 mm with gross distal radioulnar joint instability relative to the contralateral wrist were included in this study. Group 1 consisted of patients in whom the ulnar styloid base fracture was treated with conventional tension band wiring techniques. Group 2 patients were treated with a supplemental outrigger from the external fixator to the ulna and locked in 60 degrees of forearm supination. Groups 1 and 2 had an average follow-up period of 40 and 36 months, respectively. Group 2 had significantly better supination than group 1. In terms of functional outcome it was found that there was no significant difference for the Disabilities of the Arm, Shoulder, and Hand and the Gartland and Werley scores between the 2 treatment groups. There was a lower rate of complications and fewer secondary procedures were required in group 2. The incidence of distal ulna resection was 4 of the 35 patients (2 patients in each group). Our results indicate that patients in whom the ulnar styloid can be reduced and maintained in supination can be treated effectively with fixed supination outrigger external fixation. This method resulted in a statistically significant improvement in supination and a lower rate of distal radioulnar joint complications, and it required fewer secondary procedures.

Use of hinged transarticular external fixation for adjunctive joint stabilization in dogs and cats: 14 cases (1999–2003)

To describe placement of hinged transarticular external fixation (HTEF) frames and evaluate their ability to protect the primary repair of unstable joints while allowing joint mobility in dogs and cats. Retrospective study. 8 cats and 6 dogs. HTEF frames were composed of metal or epoxy connecting rods and a hinge. Measurements of range of motion of affected and contralateral joints and radiographs were made after fixator application and removal. 9 animals (4 cats and 5 dogs) had tarsal and 5 (4 cats and 1 dog) had stifle joint injuries. Treatment duration ranged from 45 to 100 days (median, 57 days). Ranges of motion in affected stifle and tarsal joints were 57% and 72% of control while HTEF was in place and 79% and 84% of control after frame removal. Complications were encountered in 3 cats and 2 dogs and included breakage of pins and connecting rods, hinge loosening, and failure at the hinge-epoxy interface. HTEF in animals with traumatic joint instability provided adjunctive joint stabilization during healing and protection of the primary repair and maintained joint motion during healing, resulting in early weight bearing of the affected limb.

Motor unit synchronization between medial and lateral vasti muscles

Objective Accurate neuromuscular control of the patellofemoral joint is important in knee joint mechanics. Strategies to coordinate the vasti muscles, such as motor unit synchronization, may simplify control of patellar tracking. This study investigated motor unit synchronization between vastus medialis (VM) and lateralis (VL). Methods Electromyographic (EMG) recordings of single motor unit action potentials (MUAPs) were made from VM and single- and multi-unit recordings were made from VL. Synchronization was quantified from peaks in the cross-correlogram generated from single MUAP pairs in VL and VM. The proportion of motor units in VM with synchronized firing in VL was also quantified from peaks in averages of multiunit VL EMG triggered from the VM MUAP. Results A high degree of synchronization of motor unit firing between VM and VL was identified. Results were similar for cross-correlation (∼45% of cases) and triggered averages (∼41% of cases). Conclusions The data suggest that synchronization between VM and VL is higher than expected. Agreement between traditional cross-correlation and triggered averaging methods suggest that this new technique may provide a more clinically viable method to quantify synchronization. Significance High synchronization between VM and VL may provide a solution to simplify control of the mechanically unstable patellofemoral joint.

Interposition Arthroplasty With Bone-Tendon Allograft: A Technique for Treatment of the Unstable Sternoclavicular Joint

Sternoclavicular joint instability is an uncommon but challenging clinical problem for the orthopaedic surgeon. Although most cases can be treated nonoperatively with minimal long-term pain or functional limitation, a small percentage may require surgical intervention. This includes chronic anterior instability associated with persistent pain or functional limitation as well as irreducible or recurrent posterior instability. Although numerous procedures have been described for treatment of the unstable sternoclavicular joint, the optimal method for stabilization has not been determined. Here we describe a technique using Achilles tendon allograft to create an interpositional arthroplasty and briefly present 3 illustrative cases in which we performed the procedure. We believe this method effectively stabilizes the joint, restores function, relieves pain, and has applications for traumatic sternoclavicular instability as well as instability related to other etiologies.

Dynamic intradigital external fixation for proximal interphalangeal joint fracture dislocations

Many skeletal traction devices have been described to treat fracture dislocations of the proximal interphalangeal (PIP) joint. Most of these techniques are technically challenging or involve cumbersome frames. We present a design modification that enhances the stability of a simple dynamic fixation system described previously and report our results with this technique. A previously described simple dynamic fixator with no rubber bands was applied to 6 patients who sustained fracture dislocations of the PIP joint. The middle finger was involved in 3 patients, the ring finger in 1 patient, and the small finger in 2 patients. The average age of the patients was 27 years (range, 21-42 y). The average involvement of the base of the middle phalanx was 48% (range, 35% to 60%). The average time from the injury to the surgery was 6 days (range, 1-14 d). The average follow-up period was 24 months (range, 7-43 mo). Immediate active flexion extension was allowed and the fixator was removed after 3 to 4 weeks. The average range of motion of the PIP joint at the final follow-up evaluation was 5 degrees to 89 degrees (range, 0 degrees to 100 degrees ). Two patients developed pin track infection that resolved with oral antibiotics. Only one patient complained of mild pain with extreme flexion. Proper reduction and congruency of the joint was noted on final anteroposterior and lateral radiographs. A simple dynamic fixator for the treatment of unstable PIP joint fracture dislocations was used successfully in 6 digits to maintain reduction and restore digital range of motion. The addition of modifications to the original technique not only improves the solidity of the construct but also provides satisfactory functional results. Based on our experience we recommend this easy technique to treat fracture dislocations of the PIP joint.

The Operative Treatment of the Unstable Distal Radioulnar Joint using Adam's Technique

Purpose: To determine the value of an anatomic distal radio-ulnar joint ligament reconstruction (Adam's technique) in patients who suffer chronic pain related to distal radio-ulnar joint instability. Materials and Methods: Twelve patients who suffered from chronic pain related to distal radio-ulnar instability and underwent a reconstruction of the distal radio-ulnar ligament using a free tendon technique were enrolled in this study. The mean follow up period was at least 1 year. In all cases, injury to the distal radio-ulnar joint was present, which had been previously treated with conservatively. There was no evidence of arthritis on the distal radio-ulnar joint radiologically. The radiological radio-ulnar space and displacement of the ulnar head, clinical pain, stability, the range of motion and the grip power were measured before and after surgery (follow up 1 year). Results: No displacement of the distal radio-ulnar joint or prominence of the ulnar head was observed radiologically in 10 cases, and only partial subluxation was present in 2 cases. Clinically, the pain disappeared in 8 cases and the stability of the joint was recovered in 8. The mean pronation, supination range and grip power increased by an average of 73, 71 degrees and 11.7 kg, respectively. Conclusion: In treating distal radio-ulnar joint instability related to chronic pain, Adam's technique using palmaris longus, which is an operation using a single incision, and by restoring the distal radio-ulnar ligament anatomically can decrease the level of pain and recover the range of motion. Therefore, it is a good method worth considering in this situation.

Sonographische Stabilitätsbeurteilung des ersten Metatarsocuneiformgelenks

Summary Instability of the first metatarsocuneiform joint (1. MC joint) has been suggested to contribute to the cause and progression of hallux valgus deformity. In hallux valgus surgery, decision making is based on the determination of the stability of the 1. MC joint. Attempts to establish the degree of stability of the 1. MC joint have not been quantitated. Several radiologic methods exist; however, determination of the threshold is still missing. The purpose of this study was to develop a sonographic method to measure the mobility of the 1. MC joint. Hypermobility of the first ray was diagnosed by stabilizing the lesser metatarsals and manipulating the first metatarsal head into maximum dorsiflexion. Elevation of the first metatarsal head greater than 5 mm dorsal to the second metatarsal constitutes hypermobility. Based on a physical examination, patients (50 feet) with a hallux valgus deformity have been categorized into 2 groups: A: Hypermobile 1. MC joint, B: Stable 1. MC joint. We used a 55 N static force on the forefoot to determine motion of the 1. MC joint. Sono-graphically a metatarsocuneiform angle was determined. A ratio q represented the relationship of the metatarsocuneiform angle with and without force application on the forefoot. For group A the mean q value was calculated with 2.14, for group B q was calculated with 1.34 (p 1.7 represented unstable joints.

Getting the Dog Moving After Surgery

Getting the Dog Moving After Surgery

Changes in ground reaction force during jump landing in subjects with functional instability of the ankle joint

Objective. To identify changes in ground reaction force during jump landing in subjects with functional instability of the ankle joint. Design. Comparison of ground reaction force during jump landing between subjects with functional instability and healthy controls. Background. We have recently demonstrated significantly altered patterns of ankle and knee movement immediately pre- and post-impact in subjects with functional instability compared to healthy controls. We now examine the changes in timing and magnitude of forces sustained by the unstable ankle during jump landing. Methods. Fourteen subjects with unstable ankles and 10 age, sex and activity matched controls performed five single leg jumps onto a force platform whilst ground reaction forces were sampled. Timing and magnitudes of forces during the first 150 ms following impact were analysed and compared between groups. Results. Lateral and anterior force peaks occurred significantly earlier in subjects with functional instability. Significant differences were seen between groups' time-averaged vertical, frontal and sagittal components of ground reaction force. These ranged from 5% (frontal force) to 100% (vertical force) of body mass. These changes occur immediately post-impact and too early for reflex correction/modification. Conclusions. The disordered force patterns observed in subjects with functional instability are likely to result in repeated injury due to significant increase in stress on ankle joint structures during jump landing. We suggest that they are most likely to result from deficits in feed-forward motor control. Relevance These results identify the potentially injurious nature of the changes in the forces applied to the unstable ankle joint during jump landing. The timing of these changes suggests that they are caused by a motor control deficit. Treatment approaches aimed at retraining feed-forward control of ankle joint movement could succeed in restoring more normal patterns of force absorption and reduce the occurrence of repeated micro-trauma to ankle structures.

The carpometacarpal joint of the thumb: stability, deformity, and therapeutic intervention.

The carpometacarpal (CMC) of the thumb is a saddle joint that permits a wide range of motion and is largely responsible for the characteristic dexterity of human prehension. This joint, located at the very base of the thumb, is subject to large physical stresses throughout life. Osteoarthritis (posttraumatic or idiopathic), rheumatoid arthritis, and postmenopausal laxity of the capsular ligaments can predispose structural instability and impairment of this important joint. The instability is characterized by varying and often progressive dislocation of the joint surfaces, resulting in a displaced axis of rotation and abnormal actions of thumb muscles. The main consequence of the instability is most often pain and weakness, most notably during pinch and grasping actions. This paper is conceptually divided into 2 sections. The first section describes the anatomic structures that maintain stability in the normal CMC joint of the thumb and how disease or trauma can cause instability and ultimate deformity. The second section describes both nonsurgical and surgical interventions that are most often used to treat an unstable CMC joint. This paper is intended primarily as an overview for the physical therapist who does not specialize in the treatment of the hand, although desires basic information on this important topic.

Translational stiffness of the replaced shoulder joint

Results after a total shoulder arthroplasty in rheumatoid patients are poor, indicated by loosening of especially the glenoid component, bad joint functionality and the possibility of a joint dislocation. The failure mechanisms behind this are multiple, including patient, surgical and design factors. These results must be improved. At present, the optimal geometrical prosthesis component design, focused on joint conformity and constraint, still has to be investigated. Proper understanding of the effect of geometrical design parameters on the theoretical relationship between joint translations and joint forces may contribute to improved designs. The main objective of this study is to theoretically describe this relationship and to investigate the joint translational stiffness, which can be used to investigate the effect of design parameters on joint motion. Joint translational stiffness is the gradient of the subluxation force with respect to the humeral head displacement. For this static analysis a potential field is introduced, as the result of a joint compressive force (muscle forces) and a subluxation force (external forces). The positive and negative stiffness during articulation inside and subluxation outside the glenoid cavity, lead to stable and unstable equilibrium joint positions, respectively. A most lateral position of the humeral head centre coincides with a zero subluxation force; at this position the humerus is dislocated and a restoring force is needed to relocate the humeral head. Joint conformity and compression force influence the joint translational stiffness during articulation inside the glenoid cavity, whereas during articulating outside the glenoid cavity this is influenced by the joint compression force and humeral radius of curvature. The glenoid radius of curvature influences the contact point and, in combination with the glenoid superior–inferior chord length, it also influences the constraintness angle, which influences the maximum allowable subluxation load to prevent a joint dislocation. This constraintness angle together with the joint conformity also influences maximum joint translations before articulation outside the glenoid cavity. Furthermore, the sign of the joint translational stiffness determines the stability of shoulder motion, which is stable and unstable if this stiffness is positive and negative, respectively.