1. The literature on hyperextension injuries of the spine is briefly reviewed. 2. Such injuries in the cervical spine can be subdivided into five groups based on the pathological anatomy, based on the experience of fifty-one patients in the Spinal Injuries Centre for Victoria over the past five years. 3. Extension injuries of the thoraco-lumbar spine are discussed. They are rare and have a poor prognosis. 4. The importance of treatment based on sound clinical and pathological knowledge is emphasised, particularly in order that stable and unstable lesions may be recognised early and managed correctly

Ankylosing spondylitis (AS) is a progressive multisystem chronic inflammatory disorder. The hallmark of this pathological process is a progressive fusion of the zygapophyseal joints and disc spaces of the axial skeleton, leading to a rigid kyphotic deformity and positive sagittal balance. The ankylosed spine is unable to accommodate normal mechanical forces, rendering it brittle and susceptible to injury. Traumatic hyperextension injury of the cervical spine leading to atlantoaxial subluxation (AAS) in AS patients can often be fatal. We report a non-traumatic mechanism of injury in AS progressing to AAS attributable to persistent hyperextension, which resulted in fatal migration of C2 through the foramen magnum. Cite this article: Bone Joint J 2013;95-B:206–9

1. The clinical and post-mortem findings are described of a patient who sustained a hyperextension injury of the neck with paraplegia. 2. There was no radiological evidence of fracture: osteoarthritis of the spine was present. 3. Evidence is presented that the cord was damaged from behind by the lamina of the vertebra below a tear in the anterior longitudinal ligament

1. The literature on paraplegia complicating hyperextension injuries of the cervical spine is reviewed, and the lack of any definite explanation of the mode of interference with cord function is noted. 2. A case is described in which a detailed dissection of the post-mortem specimen was carried out. On the basis of the findings it is suggested that one cause of the suppression of cord function in such injuries is thrombosis of the spinal arteries and liquefaction-necrosis of the cord

1) A case is reported of paraplegia with normal radiographic appearances in which cervical cord damage was shown at autopsy to have been due to hyperextension injury. 2) The mechanism of such injuries is discussed, together with the differential diagnosis from acute prolapse of an intervertebral disc. 3) The grave dangers of using the fully extended position of the cervical spine in the management of these cases is noted

Aims. Traumatic central cord syndrome (CCS) typically follows a hyperextension injury and results in motor impairment affecting the upper limbs more than the lower, with occasional sensory impairment and urinary retention. Current evidence on mortality and long-term outcomes is limited. The primary aim of this study was to assess the five-year mortality of CCS, and to determine any difference in mortality between management groups or age. Methods. Patients aged ≥ 18 years with a traumatic CCS between January 2012 and December 2017 in Wales were identified. Patient demographics and data about injury, management, and outcome were collected. Statistical analysis was performed to assess mortality and between-group differences. Results. A total of 65 patients were identified (66.2% male (n = 43), mean age 63.9 years (SD 15.9)). At a minimum of five years’ follow-up, 32.3% of CCS patients (n = 21) had died, of whom six (9.2%) had died within 31 days of their injury. Overall, 69.2% of patients (n = 45) had been managed conservatively. There was no significant difference in age between conservatively and surgically managed patients (p = 0.062). Kaplan-Meier analysis revealed no significant difference in mortality between patients managed conservatively and those managed surgically (p = 0.819). However, there was a significant difference in mortality between the different age groups (< 50 years vs 50 to 70 years vs > 70 years; p = 0.001). At five years’ follow-up, 55.6% of the patient group aged > 70 years at time of injury had died (n = 15). Respiratory failure was the most common cause of death (n = 9; 42.9%). Conclusion. Almost one-third of patients with a traumatic CCS in Wales had died within five years of their injury. The type of management did not significantly affect mortality but their age at the time of injury did. Further work to assess the long-term functional outcomes of surviving patients is needed to generate more reliable prognostic information. Cite this article: Bone Joint J 2023;105-B(8):920–927

We assessed hyperextension of the knee and joint laxity in 169 consecutive patients who underwent an anterior cruciate ligament reconstruction between 2000 and 2002 and correlated this with a selected number of age- and gender-matched controls. In addition, the mechanism of injury in the majority of patients was documented. Joint laxity was present in 42.6% (72 of 169) of the patients and hyperextension of the knee in 78.7% (133 of 169). All patients with joint laxity had hyperextension of their knee. In the control group only 21.5% (14 of 65) had joint laxity and 37% (24 of 65) had hyperextension of the knee. Statistical analysis showed a significant correlation for these associations. We conclude that anterior cruciate ligament injury is more common in those with joint laxity and particularly so for those with hyperextension of the knee

The success of total knee replacement (TKR) depends on optimal soft-tissue balancing, among many other factors. The objective of this study is to correlate post-operative anteroposterior (AP) translation of a posterior cruciate ligament-retaining TKR with clinical outcome at two years. In total 100 patients were divided into three groups based on their AP translation as measured by the KT-1000 arthrometer. Group 1 patients had AP translation < 5 mm, Group 2 had AP translation from 5 mm to 10 mm, and Group 3 had AP translation >  10 mm. Outcome assessment included range of movement of the knee, the presence of flexion contractures, hyperextension, knee mechanical axes and functional outcome using the Knee Society score, Oxford knee score and the Short-Form 36 questionnaire. At two years, patients in Group 2 reported significantly better Oxford knee scores than the other groups (p = 0.045). A positive correlation between range of movement and AP translation was noted, with patients in group 3 having the greatest range of movement (mean flexion: 117.9° (106° to 130°)) (p < 0.001). However, significantly more patients in Group 3 developed hyperextension > 10° (p = 0.01). In this study, the best outcome for cruciate-ligament retaining TKR was achieved in patients with an AP translation of 5 mm to 10 mm

Twenty-two cases of paraplegia complicating injury of the cervical column have been reviewed. The vertebral injury may be due to flexion or hyperextension violence. Flexion injury—There are three types of flexion injury: 1) dislocation; 2) compression fracture of a vertebral body; 3) acute retropulsion of an intervertebral disc. Evidence is presented in support of the view that disc protrusion is the cause of the cord lesion when there is no radiographic evidence of bone injury, and in some cases at least when there is a compression fracture. Treatment is discussed and the indications for caliper traction and laminectomy are presented. Hyperextension injurv—There are two types of hyperextension injury: 1) dislocation; 2) injury to arthritic spines. Hyperextension injury of an arthritic spine is the usual cause of paraplegia in patients over fifty years of age. The mechanism of hyperextension injury is described. The possible causes of spinal cord injury, and its treatment, are discussed

1. The claw position of a finger with intrinsic paralysis is caused by the blocking effect of the transverse lamina on the long extensor. This starts as soon as the metacarpo-phalangeal joint is hyperextended, and increases with further hyperextension. Thus the long extensor loses its pull on the interphalangeal joints and allows them to flex. Therefore, in intrinsic paralysis the claw position can be prevented or cured by keeping the metacarpo-phalangeal joint in flexion, however slight, which can be done by splinting, by tenodesis or by capsulorrhaphy. 2. Replacement of the intrinsics by some active element, although it may improve the action of the fingers, is not necessary for the correction of claw finger. The function of the intrinsics in the prevention of claw finger is not to be found in their extending effect on the interphalangeal joints, but in the flexion effect on the metacarpo-phalangeal joint, or at least in preventing its hyperextension. This is in accordance with the fact that loss of intrinsic function is disastrous only in supple fingers, in which the metacarpo-phalangeal joints tend to assume extreme degrees of hyperextension (Riordan 1953, Brand 1958). In such fingers, the wide range of hyperextension available at the metacarpo-phalangeal joints is, of course, part of a generalised laxity of the soft parts of the fingers. These soft parts generally tend to counteract the tendency to clawing; the less their resistance, the more the human finger as a whole will tend to behave like a musculo-articular model, and such a model without intrinsics will always immediately assume the claw position

We tested the hypothesis that children who sustain a supracondylar fracture have a greater range of elbow hyperextension than those with a fracture of the distal radius. Three observers made 358 measurements in 183 children (114 boys and 69 girls). There were 119 fractures of the distal radius and 64 supracondylar fractures. Initially, the group with a supracondylar fracture appeared to have extension 1.7° greater than that of the group with fracture of the distal radius. On average, there was a maximum variation of 3° between observers. After allowing for age, gender and observer, there was no significant difference between the groups. Our study had greater than 80% power to detect a difference in hyperextension of 2° at the 5% level with the above observer variability. When age and gender are taken into account, any variation in the amount of hyperextension at the elbow is not sufficient to explain the occurrence of a supracondylar fracture

Mechanical failure because of wear or fracture of the polyethylene tibial post in posteriorly-stabilised total knee replacements has been extensively described. In this study of 12 patients with a clinically and radiologically successful NexGen LPS posteriorly-stabilised prosthesis impingement of the anterior tibial post was evaluated in vivo in three dimensions during gait using radiologically-based image-matching techniques. Impingement was observed in all images of the patients during the stance phase, although the NexGen LPS was designed to accommodate 14° of hyperextension of the component before impingement occurred. Impingement arises as a result of posterior translation of the femur during the stance phase. Further attention must therefore be given to the configuration of the anterior portion of the femoral component and the polyethylene post when designing posteriorly-stabilised total knee replacements

Aims

The aim of this study was to evaluate the reliability and validity of a patient-specific algorithm which we developed for predicting changes in sagittal pelvic tilt after total hip arthroplasty (THA).

Thirty-three Monteggia fracture-dislocations occurring in patients aged 2 to 15 years were reviewed. A follow-up of 2 to 7 years in 25 patients revealed that 88% had good to excellent results and 12% had results which were fair or poor. Closed reduction was successful in 24 of 28 cases and appeared to be very effective. Open reduction was required only for older children or when treatment was begun late. A mild hyperextension deformity at the elbow noted on follow-up of patients with anterior dislocation of the radial head seemed to support the theory that the injury is caused by hyperextension. A new classification of Monteggia fracture-dislocations in children is proposed

Initial treatment of traumatic spinal cord injury remains as controversial in 2023 as it was in the early 19th century, when Sir Astley Cooper and Sir Charles Bell debated the merits or otherwise of surgery to relieve cord compression. There has been a lack of high-class evidence for early surgery, despite which expeditious intervention has become the surgical norm. This evidence deficit has been progressively addressed in the last decade and more modern statistical methods have been used to clarify some of the issues, which is demonstrated by the results of the SCI-POEM trial. However, there has never been a properly conducted trial of surgery versus active conservative care. As a result, it is still not known whether early surgery or active physiological management of the unstable injured spinal cord offers the better chance for recovery. Surgeons who care for patients with traumatic spinal cord injuries in the acute setting should be aware of the arguments on all sides of the debate, a summary of which this annotation presents.

Cite this article: Bone Joint J 2023;105-B(4):347–355.

1. The method of treatment of a mallet finger deformity by immobilisation in a plaster in the position of hyperextension of the distal interphalangeal joint and flexion of the proximal interphalangeal joint is, on the whole, unsatisfactory because the splint is difficult to apply, it may need to be changed frequently, and it is sometimes complicated by pressure sores. 2. In many cases the deformity is still present after six weeks of adequate immobilisation, but gradual improvement from the contraction of fibrous tissue occurs for up to six months. Therefore an assessment of the results of any method of treatment should be made only after an interval of at least six months. 3. The subjective end results at the end of six months are satisfactory whether or not there has been efficient immobilisation in hyperextension. Few patients have any disability and only rarely is this sufficient to cause interference with normal activities. A high proportion of patients show slight persistent deformity and limitation of movement, and this is seemingly uninfluenced appreciably by the type or duration of treatment. 4. The only treatment necessary for most cases of mallet finger is the application of elastic adhesive strapping or a straight spatula splint in order to relieve the initial discomfort from the injury

Between July 2000 and April 2004, 19 patients with bilateral spastic cerebral palsy who required an assistive device to walk had combined lengthening-transfer of the medial hamstrings as part of multilevel surgery. A standardised physical examination, measurement of the Functional Mobility Scale score and video or instrumented gait analysis were performed pre- and post-operatively. Static parameters (popliteal angle, flexion deformity of the knee) and sagittal knee kinematic parameters (knee flexion at initial contact, minimum knee flexion during stance, mean knee flexion during stance) were recorded. The mean length of follow-up was 25 months (14 to 45). Statistically significant improvements in static and dynamic outcome parameters were found, corresponding to improvements in gait and functional mobility as determined by the Functional Mobility Scale. Mild hyperextension of the knee during gait developed in two patients and was controlled by adjustment of their ankle-foot orthosis. Residual flexion deformity > 10° occurred in both knees of one patient and was treated by anterior distal femoral physeal stapling. Two children also showed an improvement of one level in the Gross Motor Function Classification System

Cadaveric knees replaced with the Geomedic, ICLH, Marmor and Total Condylar prostheses were tested in axial compression, in rotation and in hyperextension in order to observe the strength of fixation of the tibial components. In axial compression the strengths at failure varied widely, both with any one prosthesis and between prostheses. This is attributed largely to the strength of the cancellous bone of the tibia, which was measured in each case and also varied widely. Three natural knees failed at loads of 7300, 7600 and 8300 newtons respectively, whereas the strengths of replaced knees ranged from 3000 to 15750 newtons. At least one example of each design failed at less than 7300 newtons, suggesting little or no reserve of strength. The strength of fixation was greater when the tibial prosthesis was large enough to rest on the whole cross-section of the tibia. In rotation the three prostheses embodying rollers in troughs were stiffer than the Marmor which had a nearly flat tibial-bearing surface. The presence or absence of the cruciate ligaments had a negligible effect on torsional stiffness. In hyperextension, knees replaced with the ICLH, Marmor and Total Condylar prostheses failed by rupture of the posterior capsule at moments of about 60 newton-metres, compared with about 100 for natural knees. With the Marmor prosthesis the anterior cruciate ligament was avulsed at about 20 newton-metres compared with about 75 in natural knees, suggesting that in this respect the retention of the cruciate ligaments contributes little. None of the four knees tested after inserting a Geomedic prosthesis showed strengths as high as those replaced with the other three designs

1. The range of variation in full extension at the interphalangeal and metacarpo-phalangeal joints of the thumbs of 133 male and 100 female Europeans, and of 31 male Indians and 30 male Africans, has been investigated. 2. There is considerable variation between individuals in the maximum extension of both joints of the right and left thumbs in all groups studied. 3. The distribution for each joint in both thumbs in all groups is fairly symmetrical. 4. There is a high correlation between the right and left thumbs for both joints in all groups. 5. The mean angle of extension at the right and left metacarpo-phalangeal joints in all groups is similar. Female Europeans, however, show a significantly greater mean angle than male Europeans. 6. The mean interphalangeal angle of extension in male Europeans is significantly greater than that in female Europeans and the mean in the Indian and African groups is significantly greater than in the male European group. 7. There is slight negative correlation between the metacarpo-phalangeal angle and interphalangeal angle in each thumb in the European groups. 8. Many subjects in all groups can increase extension at the metacarpo-phalangeal joint after flexing the carpo-metacarpal joint. Marked hyperextension (over 40°) is more frequent in the left than in the right thumb, in females than in males, and in male Indians than in male Europeans and Africans. 9. Maximum extension at the interphalangeal joints is not related to the presence of a sesamoid bone in the anterior part of the capsule of the joint. 10. The surfaces of the metacarpo-phalangeal joints vary considerably in shape. Those which are flat form about 10 per cent. of the sample and do not show hyperextension. 11. The factors influencing the amount of extension at the interphalangeal joint is the degree of laxity of the anterior capsule. The problem at the metacarpo-phalangeal joint is more complex; both the capsule and the shape of the joint surfaces play important roles