In the assessment of fracture healing by monitoring stiffness with vibrational analysis or instrumented external fixators, it has been assumed that there is a workable correlation between stiffness and strength. We used four-point bending tests to study time-related changes in stiffness and strength in healing tibial fractures in sheep. We aimed to test the validity of the measurement of stiffness to assess fracture strength. At each duration of healing examined, we found marked variations in stiffness and strength. Stiffness was shown to be load-dependent: measurements at higher loads reflected ultimate strength more accurately. There was a biphasic relationship between stiffness and strength: at first there was a strong correlation regardless of loading conditions, but in the second phase, which included the period of ‘clinical healing’, stiffness and strength were not significantly correlated. We conclude that the monitoring of stiffness is useful primarily in assessing progress towards union but is inherently limited as an assessment of strength at the time of clinical union. Any interpretation of stiffness must take into account the load conditions

Introduction. Stiffness of the knee after total knee arthroplasty (TKA) impairs knee function and reduces patient satisfaction. Limited preoperative range of motion (ROM) and a diagnosis of osteoarthritis seem to be associated with postoperative stiffness, and medical comorbidities such as diabetes mellitus have been discussed as predisposing factors. The present study was undertaken in order to analyse both patient-related and surgical factors that could be associated with the need for mobilization under anaesthesia (MUA) after TKA. Methods. We designed a case-control-study and extracted the study population from our local arthroplasty register. We identified all patients in our register that required MUA following primary TKA (n=35) and then randomly selected 4 control patients for each case of MUA. Incomplete medical records resulted in the exclusion of 18 patients, leaving 157 patients. Univariate analysis was used in order to investigate differences between the two groups with respect to demographics, pre- and postoperative ROM, medical or psychiatric comorbidities, and the type of implant. Variables with a proposed influence on outcome were entered into a binary logistic regression model, and risk ratios (RR) were calculated with 95% confidence intervals (CI). Results. Regression analysis showed that age at operation, the presence of chronic obstructive lung disease (COLD), and preoperative flexion significantly affected outcome: Increasing age decreased the risk for needing MUA with a RR of 0.88 (CI 0.82–0.94, p<0.001) per year. Patients with COLD had significantly higher risk of needing MUA with a RR of 9.82 (CI 1.84–52.3, p=0.007). Impaired preoperative flexion was an important predictor of postoperative stiffness with a RR of 0.97 (CI 0.95–0.99, p=0.027), implicating that the risk for MUA decreased by approximately 3% for each additional degree of flexion. Gender, BMI, cardiovascular comorbidity, the presence of rheumatoid arthritis, diabetes mellitus, previous knee injury, and the type of implant did not significantly affect the risk for MUA. In univariate analysis, patients requiring MUA had significantly lower knee flexion at discharge than control patients (78° vs. 61°, p<0.001). Interpretation. We conclude that the presence of COLD, impaired preoperative knee flexion, and younger age increase the risk for needing MUA after primary TKA. The finding that COLD increases the risk for MUA is novel: It is known that patients with COLD have higher systemic levels of inflammatory mediators, and we are tempted to speculate that postoperative arthrofibrosis could be a result of enhanced systemic inflammatory activity. In our hands, the choice of implant and comorbidities other than COLD were not associated with an increased risk for MUA

Despite its clinical significance, metaphyseal fracture healing has received little attention in research and experimental models have been limited. In particular it is not known to what extent the mechanical environment plays a role in metaphyseal fracture healing. Recently, a new murine internal fixation plate has been developed to stabilise fractures in the distal femur under highly standardised conditions. Goal of the current study was to modify this design, in order to be able to evaluate the influence of the fixator bending stiffness on metaphyseal fracture healing in mice.

Adapting the existing single body design, resulting in low flexibility fixation, two new plates were developed with a decreased bending stiffness of approximately 65% and 45% of the original implant (100%). Pilot experiments were performed on 54 animals, whereas the mice were sacrificed and fracture healing assessed radiologically and biomechanically after 14 and 28 days.

MicroCT evaluation confirmed that the osteotomy was created in the trabecular, metaphyseal bone of the distal mouse femora. All bones showed progressive fracture healing over time, with decreased implant stiffness leading to increased periosteal callus formation.

These implants represent an important new research tool to study molecular and genetic aspects of metaphyseal fracture healing in mice under standardized mechanical conditions, in order to improve clinical treatment in challenging situations, such as in osteoporotic bone.

The aim of this study was to report the incidence of arthrofibrosis of the knee and identify risk factors for its development following a fracture of the tibial plateau. We carried out a retrospective review of 186 patients (114 male, 72 female) with a fracture of the tibial plateau who underwent open reduction and internal fixation. Their mean age was 46.4 years (19 to 83) and the mean follow-up was16.0 months (6 to 80).

A total of 27 patients (14.5%) developed arthrofibrosis requiring a further intervention. Using multivariate regression analysis, the use of a provisional external fixator (odds ratio (OR) 4.63, 95% confidence interval (CI) 1.26 to 17.7, p = 0.021) was significantly associated with the development of arthrofibrosis. Similarly, the use of a continuous passive movement (CPM) machine was associated with significantly less development of arthrofibrosis (OR = 0.32, 95% CI 0.11 to 0.83, p = 0.024). The effect of time in an external fixator was found to be significant, with each extra day of external fixation increasing the odds of requiring manipulation under anaesthesia (MUA) or quadricepsplasty by 10% (OR = 1.10, p = 0.030). High-energy fracture, surgical approach, infection and use of tobacco were not associated with the development of arthrofibrosis. Patients with a successful MUA had significantly less time to MUA (mean 2.9 months; sd 1.25) than those with an unsuccessful MUA (mean 4.86 months; sd 2.61, p = 0.014). For those with limited movement, therefore, performing an MUA within three months of the injury may result in a better range of movement.

Based our results, CPM following operative fixation for a fracture of the tibial plateau may reduce the risk of the development of arthrofibrosis, particularly in patients who also undergo prolonged provisional external fixation.

Cite this article: Bone Joint J 2015;97-B:109–14.

Introduction. Superior Labral Anterior Posterior Tears are being treated surgically in increasing numbers. Stiffness is the most common complication. We reviewed 115 cases of SLAP repairs to try and identify preoperative risk factors if any for stiffness. Methods. Retrospective cohort study of 115 patients who underwent SLAP repair. All patients failed attempts at conservative therapy including NSAIDS, Physical Therapy and cortisone injections. Results. Age ranged from 16–71 years, with an average age of 46. Male 84, Female 31. patient charts and operative notes were examined from 2004–2009. We used an average of 1.64 anchors per case; we performed arthroscopic Mumford on 15 patients, subscap repair (4), 19 cases with concomitant SLAP repair and Arthroscopic rotator cuff repair Other procedures included Biceps tenotomy and tenodesis, chondroplasty, Microfracture, removal of loose bodies, synovectomy and lysis of adhesions. Twelve patients underwent revision surgery(10%) We had 5 cases of stiffness which required lysis of adhesions and synovectomy, 4 cases had previous SLAP and concomitant rotator cuff repair done at the index surgery, 4 cases had arthrosis noted at index surgery and underwent chondroplasty and 2 of them underwent micro fracture. During the revision surgery 4 had also a concomitant cuff tear (new) which required repair Average time from index surgery to revision was 11 months, the patients who developed adhesive Capsulitis and stiffness the average age was 56 years. We had 2 titanium metal anchors pull out and present as loose bodies with one of the anchor causing chondral damage, we stopped using metal anchors and we have not had this problem recur since.5 cases had Mumford procedure done during the revision surgery.5 cases needed repeat SLAP repairs and by increasing use of biceps tenotomy this incidence should decrease. Conclusions. Our large retrospective case series shows an acceptable complication rate. Stiffness (5%) is still the most common complication especially in patients older than 50, withpreexisting Glenohumeral arthritis and concomitant rotator cuff tears. Hopefully our early aggressive mobilization will decrease this incidence

Introduction. Muscle stiffness and joint contractures are common complications of limb lengthening. Authors have demonstrated less permanent soft tissue complications with intramedullary lengthening than external fixation. Our aim was to evaluate the joint response following intramedullary femoral lengthening and need for physiotherapy and alteration to rate/rhythm of lengthening. Method. A retrospective review of documentation for all femoral Precice nails in our centre inserted between 2012 and 2017. This involved 98 nails (68 antegrade, 30 retrograde) in 88 patients (59 males, 29 females) with a mean age of 32 years (range 12–69 yrs). We excluded cases where there was no documentation regarding Range of Movement (ROM). Bilateral lengthenings were recorded as separate cases. This left 50 antegrade, 16 retrograde cases with hip ROM data and 55 antegrade, 26 retrograde cases with Knee ROM data. Results. Hip. In the antegrade group 20 cases (39%) developed no stiffness throughout treatment. ROM decreased in 61% (n=30) of cases and the median length at which this occurred was 3cm. Where a retrograde nail was inserted 62.5% of cases (n=10) maintained normal range of motion. The median length at which ROM decreased was 3.25cm, this occurred in 6 cases (37.5%). . Knee. Where the antegrade nail was inserted, 22 cases (40%) did not develop stiffness. There was reduced ROM in 33 cases (60%), occurring at a median distance of 2cm. The median distance at which reduced ROM occurred with the retrograde nails was 1.5cm, this occurred in 23 cases (88.5%). 3 cases did not develop stiffness. All cases regained full ROM. Conclusion. Although there was no permanent loss, Joint Stiffness still occurs with intramedullary limb lengthening and there remains the need for regular physiotherapy. There are no data from other institutions for comparison. Rehabilitation guidelines and a proforma to accurately monitor patients ROM throughout treatment have been developed

Introduction. Fracture healing is governed by biological and mechanical factors. Circular frames are one method to fix fractures. Recently, the number of frame designs that are available has increased and these different designs may have different effects on the mechanical environment created. The senior author has been concerned by the stability of the construction when a short frame is used. This study examined the stability of different frames and the possible use of additional 7th struts to aid stability. Method. The frame configuration was modified with increasing strut angles from 15° − 70°. Each frame was cyclically tested in compression to 200N. The Taylor Spatial Frame was retested with the addition of a seventh strut. Results. Frame stability significantly deteriorated with shorter struts. This was particularly apparent at angles less than 30°. Stiffness was significantly improved with the addition of a seventh strut. Conclusions. Ring-strut angle, plays a significant factor in hexapod frame stability. Stability can be improved with the addition of a seventh strut. This may be particularly important in the paediatric community and in frame around the thigh were a larger ring may increase the strut angle

Hypothesis. The proximal geometry and design of trochanteric nails affects initial construct stiffness, fatigue survival, and preservation of biomechanical stability over time. Materials & Methods. Eight pairs of human cadaveric femora were implanted with two different short intramedullary nails with (Intertan, (S&N)) and without (Gamma 3, (Stryker)) interlocking lag screws. Femoral osteotomies were performed to generate a pertrochanteric multifragmentary unstable fracture (OTA 31-A 2.2). The bones were tested in a cyclic testing protocol with increasing loads of 100 N every 20.000 cycles (start point 50/500 N) simulating one leg stance. The position of the femur was 10° adduction and 10° extension. Stiffness, failure load, and cycles to failure were measured. Results. Initially, stiffness of the interlocking lag screw nail was 40 % higher (p < 0,05) than for the non-interlocking nail. During the test, the difference in stiffness gradually decreased. Load to failure (9 %, p < 0,05) and cycles to failure (13 %, p < 0,05) were also higher for the interlocking nail construct. Discussion & Conclusion. The interlocking screw design of intramedullary nail constructs improves the mechanical performance in unstable trochanteric fractures. This may result in improved clinical performance

Introduction. The authors performed a short term prospective study of unicompartmental knee replacement (UKR) associated to patella-femoral arthroplasty (PFA) for the treatment of bicompartmental symptomatic knee arthritis. At the latest follow-up all the implants were matched to a similar computer assisted Total Knee Replacements (CAS-TKR) group implanted for the same indications. Hypothesis of the study was that this bicompartimental implants could achieve comparable outcomes to TKR with a more conservative surgery and a higher joint function. Materials and Methods. 19 cases of anteriomedial (12) or anterolateral (7) arthritis in 19 stable knees were prospectively involved in the study. All the knees underwent to a selective reconstruction using simultaneously both UKR and PFR using the same surgical technique. All bicompartmental implants were performed by the same surgeon. Surgical time, hospital staying and all intra and post operative complications were registered. At a minimum follow-up of 20 months, every single case was marched to a similar case where had been implanted a computer assisted cruciate retaining TKR. Criteria of matching were: sex, age, pre-operative range of motion and arthritis grade. In both the groups all the cases were assessed clinically using WOMAC, KKS and GIUM scores. All the knees were radiologically investigated using the same radiological protocol. Results. Intra operatively we did not registered any complication. No revision in both groups. The mean surgical time was 86 minutes (range: 78–121) in UKR+PFR group and 81 minutes (range: 71–112) in CAS-TKR group. There were no statistical significant differences in the hospital stay. No statistically significant difference was seen for the Knee Society, Functional and GIUM scores between the 2 groups. Statistically significant better WOMAC Function/Stiffness indexes were registered for the UKR+PFR group. CAS-TKR implants achieved a statistically better aligned mechanical axes. Conclusions. The results of this prospective short term prospective study suggest that UKR+PFR implant is a viable option for bicompartmental anteromedial arthritis at least as well as TKR but maintaining an higher level of function

Objectives

External fixators are the traditional fixation method of choice for contaminated open fractures. However, patient acceptance is low due to the high profile and therefore physical burden of the constructs. An externalised locking compression plate is a low profile alternative. However, the biomechanical differences have not been assessed. The objective of this study was to evaluate the axial and torsional stiffness of the externalised titanium locking compression plate (ET-LCP), the externalised stainless steel locking compression plate (ESS-LCP) and the unilateral external fixator (UEF).

Radiological evidence of post-traumatic osteoarthritis (PTOA) after fracture of the tibial plateau is common but end-stage arthritis which requires total knee arthroplasty is much rarer.

The aim of this study was to examine the indications for, and outcomes of, total knee arthroplasty after fracture of the tibial plateau and to compare this with an age and gender-matched cohort of TKAs carried out for primary osteoarthritis.

Between 1997 and 2011, 31 consecutive patients (23 women, eight men) with a mean age of 65 years (40 to 89) underwent TKA at a mean of 24 months (2 to 124) after a fracture of the tibial plateau. Of these, 24 had undergone ORIF and seven had been treated non-operatively. Patients were assessed pre-operatively and at 6, 12 and > 60 months using the Short Form-12, Oxford Knee Score and a patient satisfaction score.

Patients with instability or nonunion needed total knee arthroplasty earlier (14 and 13.3 months post-injury) than those with intra-articular malunion (50 months, p < 0.001). Primary cruciate-retaining implants were used in 27 (87%) patients. Complication rates were higher in the PTOA cohort and included wound complications (13% vs 1% p = 0.014) and persistent stiffness (10% vs 0%, p = 0.014). Two (6%) PTOA patients required revision total knee arthroplasty at 57 and 114 months. The mean Oxford knee score was worse pre-operatively in the cohort with primary osteoarthritis (18 vs 30, p < 0.001) but there were no significant differences in post-operative Oxford knee score or patient satisfaction (primary osteoarthritis 86%, PTOA 78%, p = 0.437).

Total knee arthroplasty undertaken after fracture of the tibial plateau has a higher rate of complications than that undertaken for primary osteoarthritis, but patient-reported outcomes and satisfaction are comparable.

Cite this article: Bone Joint J 2015;97-B:532–8.

This article presents a unified clinical theory that links established facts about the physiology of bone and homeostasis, with those involved in the healing of fractures and the development of nonunion. The key to this theory is the concept that the tissue that forms in and around a fracture should be considered a specific functional entity. This ‘bone-healing unit’ produces a physiological response to its biological and mechanical environment, which leads to the normal healing of bone. This tissue responds to mechanical forces and functions according to Wolff’s law, Perren’s strain theory and Frost’s concept of the “mechanostat”. In response to the local mechanical environment, the bone-healing unit normally changes with time, producing different tissues that can tolerate various levels of strain. The normal result is the formation of bone that bridges the fracture – healing by callus. Nonunion occurs when the bone-healing unit fails either due to mechanical or biological problems or a combination of both. In clinical practice, the majority of nonunions are due to mechanical problems with instability, resulting in too much strain at the fracture site. In most nonunions, there is an intact bone-healing unit. We suggest that this maintains its biological potential to heal, but fails to function due to the mechanical conditions. The theory predicts the healing pattern of multifragmentary fractures and the observed morphological characteristics of different nonunions. It suggests that the majority of nonunions will heal if the correct mechanical environment is produced by surgery, without the need for biological adjuncts such as autologous bone graft.

Cite this article: Bone Joint J 2016;98-B:884–91.

Aims

The aim of this study was to report the outcome following primary fixation or a staged protocol for type C fractures of the tibial plafond.

We investigated a new intramedullary locking nail that allows the distal interlocking screws to be locked to the nail. We compared fixation using this new implant with fixation using either a conventional nail or a locking plate in a laboratory simulation of an osteoporotic fracture of the distal femur. A total of 15 human cadaver femora were used to simulate an AO 33-A3 fracture pattern. Paired specimens compared fixation using either a locking or non-locking retrograde nail, and using either a locking retrograde nail or a locking plate. The constructs underwent cyclical loading to simulate single-leg stance up to 125 000 cycles. Axial and torsional stiffness and displacement, cycles to failure and modes of failure were recorded for each specimen. When compared with locking plate constructs, locking nail constructs had significantly longer mean fatigue life (75 800 cycles (sd 33 900) vs 12 800 cycles (sd 6100); p = 0.007) and mean axial stiffness (220 N/mm (sd 80) vs 70 N/mm (sd 18); p = 0.005), but lower mean torsional stiffness (2.5 Nm/° (sd 0.9) vs 5.1 Nm/° (sd 1.5); p = 0.008). In addition, in the nail group the mode of failure was either cut-out of the distal screws or breakage of nails, and in the locking plate group breakage of the plate was always the mode of failure. Locking nail constructs had significantly longer mean fatigue life than non-locking nail constructs (78 900 cycles (sd 25 600) vs 52 400 cycles (sd 22 500); p = 0.04).

The new locking retrograde femoral nail showed better stiffness and fatigue life than locking plates, and superior fatigue life to non-locking nails, which may be advantageous in elderly patients.

Cite this article: Bone Joint J 2014;96-B:114–21.

Fractures of the distal radius occurring in young adults are treated increasingly by open surgical techniques, partly because of concern that failure to restore the alignment of the fracture accurately may cause symptomatic post-traumatic osteoarthritis in future years. We reviewed 106 adults who had sustained a fracture of the distal radius between 1960 and 1968 and who were below the age of 40 years at the time of injury. We carried out a clinical and radiological assessment at a mean follow-up of 38 years (33 to 42).

No patient had required a salvage procedure. While there was radiological evidence of post-traumatic osteoarthritis after an intra-articular fracture in 68% of patients (27 of 40), the disabilities of the arm, shoulder and hand (DASH) scores were not different from population norms, and function, as assessed by the Patient Evaluation Measure, was impaired by less than 10%. Ordinal logistic regression analysis showed a significant relationship between narrowing of the joint space and extra-articular malunion (dorsal angulation and radial shortening) as well as intra-articular injury. Multivariate analysis revealed that grip strength had fallen to 89% of that of the uninjured side in the presence of dorsal malunion, but no measure of extra-articular malunion was significantly related to either the Patient Evaluation Measure or DASH scores.

While anatomical reduction is the principal aim of treatment, imperfect reduction of these fractures may not result in symptomatic arthritis in the long term, and this should be considered when counselling patients on the risks and benefits of the many treatment options available.